ath10k: use complete VHT chan width for 160MHz workaround

The ath10k firmware doesn't announce its VHT channel width capabilities in
the vht_cap information from the "service ready event" arguments. The
driver must therefore check whether the 160MHz short GI bit is set and
whether the driver still doesn't set the bits for the 160/80+80 MHz
capabilities.

The two bits for the channel width are a two bit integer and not two
separate bits which cannot be parsed without the knowledge of the other
bit. Using IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160_80PLUS80MHZ (b10..) as a
mask for this task doesn't make any sense. The correct mask for the VHT
channel width should be used instead to make this check more readable.

Signed-off-by: Ben Greear <greearb@candelatech.com>
[sven.eckelmann@openmesh.com: separate 160Mhz workaround cleanup, add commit
 message]
Signed-off-by: Sven Eckelmann <sven.eckelmann@openmesh.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>