if_ath.c: make ath_hal_reg_write_tgt more readable

Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
wmi: add extra fields to WMI_CMD_HDR

Add length and crc8 fields to idetify usb related
issues.

Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
wmi: do extra sanity check on wmi commands

Use new crc8 and lenght fileds to identify corrupt
buffers.

Right now we get corrupt commands after module reload
on some USB3 controllers.

Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>