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>