ath10k: fix qca61x4 hw2.1 support

During initialization firmware does some sort of
memory switch between DRAM and IRAM. If
configuration value for bank switching isn't
correct device crashes during init.

The new value prevents firmware 11.0.0.302 (and
possibly others) for qca61x4 hw2.1 from crashing
during init.

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