wifi: check if socket flags are valid

Checking the SOCK_WIFI_STATUS flag bit in sk_flags may give wrong results
since sk_flags are part of a union and the union is used otherwise. Add
sk_requests_wifi_status() which checks if sk is non-NULL, sk is a full
socket (so flags are valid) and checks the flag bit.

Fixes: 76a853f8 ("wifi: free SKBTX_WIFI_STATUS skb tx_flags flag")
Suggested-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Bert Karwatzki <spasswolf@web.de>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Link: https://patch.msgid.link/20250520223430.6875-1-spasswolf@web.de


[edit commit message, fix indentation]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>