iwlwifi: mvm: update firmware when MU EDCA params change

When MU EDCA params change, resend the STA_HE_CTXT command
updating the MU EDCA params.

Signed-off-by: Shaul Triebitz <shaul.triebitz@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>