wifi: iwlwifi: do not warn about a flush with an empty TX queue

When resuming it can happen that the TX queue is flushed even though it
is entirely empty. This is completely fine and should not be causing an
error level log message.

Return early from reclaim in that case.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20241008072037.7c152d0820be.I3ae39a9a470f47bfe4405f2e5c30327e157eb55f@changeid


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