wifi: wilc1000: set net device registration as last step during interface creation

net device registration is currently done in wilc_netdev_ifc_init but
other initialization operations are still done after this registration.
Since net device is assumed to be usable right after registration, it
should be the very last step of initialization.

Move netdev registration at the very end of wilc_netdev_ifc_init to let
this function completely initialize netdevice before registering it.

Signed-off-by: Alexis Lothoré <alexis.lothore@bootlin.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20240514-mac_addr_at_probe-v2-1-afef09f1cd10@bootlin.com