iwlwifi: fw: do not set sgi bits for HE connection

If the association supports HE, HT/VHT rates will never be used for Tx
and therefore there's no need to set the sgi-per-channel-width-support
bits, so don't set them in this case.

Fixes: 110b32f0 ("iwlwifi: mvm: rs: add basic implementation of the new RS API handlers")
Signed-off-by: Naftali Goldstein <naftali.goldstein@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>