iwlwifi: mvm: add definitions for new rate & flags

As a part of preparing to the new rate & flags,
add new needed definitions.

Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20211017123741.41563bea6610.I51a886fa75cca723c81877b386ba41b2a9db1122@changeid


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