Part of ath6kl uses "REV3" style of naming hardware versions and elsewhere
"hw 2.1.1" is used instead for the same version. This is confusing, use
the latter term everywhere.
Signed-off-by: NKalle Valo <kvalo@qca.qualcomm.com>

Add USB support for ar6004. Currently only firmware can be booted,
no commands can be sent to firmware yet as HTC layer doesn't work
with USB yet.

Based on patches by Kevin Fang.
Signed-off-by: NKalle Valo <kvalo@qca.qualcomm.com>