wifi: rt2x00: soc: modernize probe

wifi: rt2x00: soc: modernize probe

Remove a bunch of static memory management functions and simplify with
devm.

Also move allocation before ieee80211_alloc_hw to get rid of goto
statements and clarify the error handling a bit more.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Acked-by: Stanislaw Gruszka <stf_xl@wp.pl>
Reviewed-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://patch.msgid.link/20250722212856.11343-6-rosenp@gmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>