iwlwifi: mvm: rs: start using LQ command color

Up until now, the driver was comparing the rate reported by the FW and
the rate of the latest LQ command to avoid processing data belonging
to the old LQ command. Recently, FW changed the meaning of the initial
rate field in tx response and it holds the actual rate (which is not
necessarily the initial rate of LQ's rate table). Use instead LQ cmd
color to be able to filter out tx responses/BA notifications which
where sent during earlier LQ commands' time frame.

This fixes some throughput degradation in noisy environments.

Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>