siflower: 6.12: apply trivial driver fixes

siflower: 6.12: apply trivial driver fixes

Apply trivial fixes for 6.12 files:
- Make functions static
- Add lots of missing header in drivers
- Fix no newline at end of file error and other new line error
- Drop deprecated validate function for xgmac
- Use devm for stmmac probe
- Remove host_ prefix from pcie_host_ops

Tested-by: Jingkun Zheng <[email protected]>
Tested-by: Zhu Yujie <[email protected]>
Tested-by: Chuanhong Guo [email protected]
Signed-off-by: Zhu Yujie <[email protected]>
[ improve commit description ]
Link: https://github.com/openwrt/openwrt/pull/20555
Signed-off-by: Christian Marangi <[email protected]>