HE: Fix HE capability check for PPE threshold present

The the mask for PPE threshold present in the HE phy capability byte 6 is
0x80 and not 0x6. This incorrect mask breaks the length calculation and as
result the acceptance of the HE capabilities for STAs which either:

* don't have the PPE threshold present bit set AND the Codebook Size={7,5}
  MU Feedback or the Triggered SU Beamforming feedback bit set

* do have the PPE threshold present set AND neither the Codebook Size={7,5}
  MU Feedback nor the Triggered SU Beamforming feedback bit set

Fixes: 8f5fc369e2 ("HE: Fix HE Capabilities element variable length encoding")
Signed-off-by: Sven Eckelmann <seckelmann@datto.com>

src/ap/ieee802_11_he.c

@@ -23,7 +23,7 @@ static u8 ieee80211_he_ppet_size(u8 ppe_thres_hdr, const u8 *phy_cap_info)
 	u8 sz = 0, ru;
 
 	if ((phy_cap_info[HE_PHYCAP_PPE_THRESHOLD_PRESENT_IDX] &
-	     HE_PHYCAP_PPE_THRESHOLD_PRESENT_IDX) == 0)
+	     HE_PHYCAP_PPE_THRESHOLD_PRESENT) == 0)
 		return 0;
 
 	ru = (ppe_thres_hdr >> HE_PPE_THRES_RU_INDEX_BITMASK_SHIFT) &