iwlwifi: mvm: add a flag to reduce power command.

Add a flags bitfield in REDUCED_TX_POWER_CMD, and
send it as is to FW.

Signed-off-by: Ayala Barazani <ayala.barazani@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20220304131517.55c2f014f5ee.Iceb632f620de959800f979e212f0dc20240f9d38@changeid


Signed-off-by: Luca Coelho <luciano.coelho@intel.com>