iwlwifi: rs-fw: support dcm

Add flags to the tlc_cfg_cmd for signaling peer support for receiving
Dual Carrier Modulation at BPSK (MCS 0), and set them according to peer
capabilities.

Signed-off-by: Naftali Goldstein <naftali.goldstein@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>