wifi: iwlwifi: mvm: rename BTM support flag and its TLV

Currently, we only need to support BTM rejection.
However, in the future we might want to support other BTM modes.
Rephrase its naming.

Signed-off-by: Haim Dreyfuss <haim.dreyfuss@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230613155501.ad20f10668d1.Icbb3fbae50b2302b97225b183dd336b02a4f37ee@changeid


Signed-off-by: Johannes Berg <johannes.berg@intel.com>