airoha: fix PHY_DETACH_NO_HW_RESET patch panic

airoha: fix PHY_DETACH_NO_HW_RESET patch panic

Fix kernel panic caused by downstream PHY_DETACH_NO_HW_RESET patch.

[   20.994001] airoha_eth 1fb50000.ethernet wan: validation of usxgmii with support 00,00000000,00000000,00006000 and advertisement 00,00000000,00000000,00006000 failed: -EINVAL
[   21.058106] Unable to handle kernel access to user memory outside uaccess routines at virtual address 00000000000000b8
[   21.068879] Mem abort info:
[   21.071684]   ESR = 0x0000000096000005
[   21.075436]   EC = 0x25: DABT (current EL), IL = 32 bits
[   21.080790]   SET = 0, FnV = 0
[   21.083854]   EA = 0, S1PTW = 0
[   21.086997]   FSC = 0x05: level 1 translation fault
[   21.091931] Data abort info:
[   21.094829]   ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
[   21.100359]   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
[   21.105419]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[   21.110762] user pgtable: 4k pages, 39-bit VAs, pgdp=0000000091bc8000
[   21.117218] [00000000000000b8] pgd=0800000084ee9003, p4d=0800000084ee9003, pud=0800000084ee9003, pmd=0000000000000000
[   21.127892] Internal error: Oops: 0000000096000005 [#1] SMP
[   21.133483] Modules linked in: pppoe ppp_async nft_fib_inet nf_flow_table_inet pppox ppp_generic nft_reject_ipv6 nft_reject_ipv4 nft_reject_inet nft_reject nft_redir nft_quota nft_numgen nft_nat nft_masq nfte
[   21.191941] CPU: 3 UID: 0 PID: 1882 Comm: netifd Tainted: G           O       6.12.57 #0
[   21.200046] Tainted: [O]=OOT_MODULE
[   21.203534] Hardware name: Gemtek W1700K (DT)
[   21.207892] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[   21.214861] pc : phy_detach+0xe8/0x194
[   21.218628] lr : phy_detach+0xe4/0x194
[   21.222387] sp : ffffffc0823ebae0
[   21.225702] x29: ffffffc0823ebae0 x28: ffffff8005451c00 x27: 0000000000000000
[   21.232846] x26: 0000000000000000 x25: 0000000000001003 x24: ffffffc080cf8240
[   21.239990] x23: 0000000000001002 x22: ffffff807fc527f8 x21: ffffffc080c93318
[   21.247125] x20: ffffff8001cfc000 x19: ffffff80036f7000 x18: ffffff8012cde323
[   21.254269] x17: 303a302d30333537 x16: 000000000000000e x15: 0000005139b64de4
[   21.261413] x14: 0000000000000001 x13: ffffff80020b46c0 x12: 0000000000000001
[   21.268550] x11: ffffff80020b46c0 x10: ffffff8005451cc0 x9 : ffffff807dbf5200
[   21.275694] x8 : ffffff80020b46c0 x7 : ffffff80010a8ed0 x6 : 0000000000000000
[   21.282838] x5 : 00000000000013f8 x4 : 0000000000000000 x3 : ffffff8005451c00
[   21.289983] x2 : 0000000000000000 x1 : ffffff8005451c00 x0 : 0000000000000000
[   21.297128] Call trace:
[   21.299575]  phy_detach+0xe8/0x194
[   21.302988]  phylink_fwnode_phy_connect+0x194/0x1c0
[   21.307874]  phylink_of_phy_connect+0x18/0x20
[   21.312248]  airoha_dev_open+0x44/0x2b0
[   21.316094]  __dev_open+0xe8/0x15c
[   21.319505]  __dev_change_flags+0x154/0x1c0
[   21.323698]  dev_change_flags+0x20/0x64
[   21.327541]  dev_ifsioc+0x28c/0x444
[   21.331032]  dev_ioctl+0x290/0x4b8
[   21.334434]  sock_ioctl+0x31c/0x444
[   21.337923]  __arm64_sys_ioctl+0x354/0xe60
[   21.342020]  invoke_syscall.constprop.0+0x58/0xec
[   21.346725]  do_el0_svc+0x3c/0xd4
[   21.350041]  el0_svc+0x18/0x60
[   21.353097]  el0t_64_sync_handler+0x118/0x124
[   21.357455]  el0t_64_sync+0x150/0x154

Make sure the phydev have a driver before asserting a signal or we would
dereference a NULL address.

Signed-off-by: Balázs Triszka <[email protected]>
[ improve commit description ]
Link: https://github.com/openwrt/openwrt/pull/20740
Signed-off-by: Christian Marangi <[email protected]>