wifi: iwlwifi: mld: keep healthy link on EMLSR missed beacon exit

wifi: iwlwifi: mld: keep healthy link on EMLSR missed beacon exit

When EMLSR exits due to beacon loss on the current link, the driver
should keep the link that is still receiving beacons. The previous
code always called get_primary_link(), keeping the primary link
regardless of which link is actually losing beacons. If the primary
link is the one losing beacons, the driver exits EMLSR onto the
degraded link and the connection is lost eventually.

When both links lose beacons, keep the primary link. When only the
current link loses beacons -- whether due to signal loss or a BSS
parameter change -- keep the other link.

Signed-off-by: Avinash Bhatt <avinash.bhatt@intel.com>
Link: https://patch.msgid.link/20260517100550.b2d700f7775e.I8e9189ce6cf4388878beab14e56341becd5f427c@changeid
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>