carl9170 firmware: introduce per-rate ER Protection setting

Previously, the firmware has applied (or rather has stuck)
with the ERP settings of the first rate for all retry rates.
This is now history and the driver can choose between
different ERP settings for each individual retry rate.

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>

carl9170 firmware: update README

the README should include a list of all necessary
tools and libraries to build the firmware.

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>

carl9170 firmware: checkpatch fixes

Since the shared headers are meant to be included
into the kernel, they should pass checkpatch.pl
without generating hundreds of WARNINGS.

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>

carl9170 firmware: import 1.7.0

The carl9170 project aims to provide more than just a
working substitute firmware+driver for Atheros' AR9170
USB solutions.

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>