iwlwifi: mvm: fix assert 1F04 upon reconfig

When we reconfig we must not send the MAC_POWER command that relates to
a MAC that was not yet added to the firmware.

Ignore those in the iterator.

Cc: stable@vger.kernel.org
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20220517120044.ed2ffc8ce732.If786e19512d0da4334a6382ea6148703422c7d7b@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>