ath10k: Add hw param for rx ring size support

WCN3990 uses larger ring size in comparison to existing
ring size value.
Add rx ring size hw param for supporting different rx ring
size across multiple target.

Signed-off-by: Govind Singh <govinds@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>