wifi: cfg80211: verify if AP_VLAN belongs to the correct AP

The get_vlan() only checks if NL80211_ATTR_STA_VLAN target is an
AP/AP_VLAN/P2P_GO interface on the same wiphy. It has no notion of which
specific AP a given AP_VLAN belongs to.

Fix that by comparing the ethernet addresses of the two net devices.
Given VLAN A' must have the same address as AP A. Otherwise, return
error code.

Signed-off-by: Slawomir Stepien <sst@poczta.fm>
Reported-by: Johannes Berg <johannes@sipsolutions.net>
Link: https://lore.kernel.org/all/22e7ddfc50d7a6a16c437b876dab5fe223799610.camel@sipsolutions.net/
Link: https://patch.msgid.link/20260914081350.83484-1-sst@poczta.fm
Signed-off-by: Johannes Berg <johannes.berg@intel.com>