wifi: iwlwifi: mvm: don't always set antenna in beacon template cmd

This needs to be set only if the FW is not capable of selecting an
antenna on its own.

Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20240512072733.73d790911268.I158dc1dbc9c2e199c69d8213e5496d2de72da28b@changeid


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