iwlwifi: mvm: only enable HE DCM if we also support TX

Currently we enable DCM if the peer supports RX without checking whether
we advertised that we support TX.  Fix this by also checking that our TX
side is set.

Signed-off-by: Mordechay Goodstein <mordechay.goodstein@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20220129105618.6865266c8a34.If1de7849f25337bb14ba2f27896e9715ae5975df@changeid


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