IEEE80211_ADDBA_PARAM_AMSDU_MASK
capab = u16_encode_bits(amsdu, IEEE80211_ADDBA_PARAM_AMSDU_MASK);
capab = IEEE80211_ADDBA_PARAM_AMSDU_MASK;
amsdu = capab & IEEE80211_ADDBA_PARAM_AMSDU_MASK;