In the end, the firmware doesn't want the SP len as present
in the WMM IE, but rather the actual number of frames.

Fixes: bd3c6cf901a8 ("iwlwifi: mvm: tell the firmware about the U-APSD parameters")
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>