iwlwifi: mvm: support RLC configuration command

There's an RLC configuration command in the firmware that's
going to replace the chain information in the PHY context.
Add support for this command, while leaving the PHY context
fields unset when we know the RLC command will be used.

Also add support to send only the RLC configuration command
if only the # of chains used on the PHY context changes.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20211204083238.55faa3782bb0.I3f9d0071e680cab513c59b093d0827af99d41c51@changeid


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