iwlwifi: iwl-nvm-parse: set STBC flags for HE phy capabilities

Our HW supersets STBC for HE but never set it in assoc IE, fix it by
setting it and enable using it.

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.20210802170640.0108f3e322b6.Ib25a91b5c48ff1fb2185b86a9e4bf5eec637df90@changeid


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