wifi: mt76: mt7996: do not hardcode vht beamform cap

Use the sts variable when setting vht beamform sts cap.
Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7996/init.c

@@ -465,7 +465,7 @@ void mt7996_set_stream_vht_txbf_caps(struct mt7996_phy *phy)
 
 	*cap |= IEEE80211_VHT_CAP_SU_BEAMFORMEE_CAPABLE |
 		IEEE80211_VHT_CAP_MU_BEAMFORMEE_CAPABLE |
-		(3 << IEEE80211_VHT_CAP_BEAMFORMEE_STS_SHIFT);
+		FIELD_PREP(IEEE80211_VHT_CAP_BEAMFORMEE_STS_MASK, sts - 1);
 
 	*cap &= ~(IEEE80211_VHT_CAP_SOUNDING_DIMENSIONS_MASK |
 		  IEEE80211_VHT_CAP_SU_BEAMFORMER_CAPABLE |