rhashtable: fix annotations for rht_for_each_entry_rcu()

rhashtable: fix annotations for rht_for_each_entry_rcu()

Call rcu_deference_raw() directly from within rht_for_each_entry_rcu()
as list_for_each_entry_rcu() does.

Fixes the following sparse warnings:
net/netlink/af_netlink.c:2906:25:    expected struct rhash_head const *__mptr
net/netlink/af_netlink.c:2906:25:    got struct rhash_head [noderef] <asn:4>*<noident>

Fixes: e341694e3eb57fc ("netlink: Convert netlink_lookup() to use RCU protected hash table")
Signed-off-by: Thomas Graf <[email protected]>
Signed-off-by: David S. Miller <[email protected]>