wifi: iwlwifi: mvm: remove chanctx WARN_ON

During link switching there might be a link that's marked
active but has no chanctx assigned (so it's not active from
our driver's POV), skip such links in power recalculation
without any warning.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230329100039.c629090bd5d2.If7a680d5e349d454f2122f936c21522b9528a55f@changeid


Signed-off-by: Johannes Berg <johannes.berg@intel.com>