ath10k: htc: ready_ext msg support

Added support for extended ready message.
The extended ready message contains the maximum bundle
count supported by SDIO chipsets.

It is transmitted by SDIO chipset only and replaces the
"standard" ready message in this case.

Signed-off-by: Erik Stromdahl <erik.stromdahl@gmail.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>