wifi: ath9k: return by of_get_mac_address

wifi: ath9k: return by of_get_mac_address

When using nvmem, ath9k could potentially be loaded before nvmem, which
loads after mtd. This is an issue if DT contains an nvmem mac address.

If nvmem is not ready in time for ath9k, -EPROBE_DEFER is returned. Pass
it to _probe so that ath9k can properly grab a potentially present MAC
address.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://patch.msgid.link/20241105222326.194417-1-rosenp@gmail.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>