ath10k: add support for 10.2 firmware

The 10.2 firmware is a successor of 10.1 firmware
(formerly identified as 10.x). Both share a lot
but have some slight ABI differences that need to
be taken care of.

The 10.2 firmware introduces some new features but
those can be added in subsequent patches. This
patch makes ath10k boot and work with 10.2 with
comparable functionality to 10.1.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>