ath10k: update the IRAM bank number for QCA9377

Preparation for a new QCA9377 firmware release. The new firmware release
requires more IRAM banks, hence update that on ath10k.

The IRAM banks promotion won't break any backwards compatibility, as those IRAM
banks were not getting used in previous firmware releases.

Signed-off-by: Ryan Hsu <ryanhsu@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>