qcacmn: Add support for QCA6490

Add the following support for QCA6490:
1. Initialize the qca6490_hal_hw_txrx_ops
2. Initialize the hw_srng_table
3. Attach hal_qca6490_attach

Change-Id: Ic53c520ef804eb4fbe1434c704e9040c83011d3d
CRs-Fixed: 2522133

hal/wifi3.0/hal_internal.h

@@ -496,6 +496,7 @@ struct hal_soc {
 	struct hal_hw_txrx_ops *ops;
 };
 
+void hal_qca6490_attach(struct hal_soc *hal_soc);
 void hal_qca6390_attach(struct hal_soc *hal_soc);
 void hal_qca6290_attach(struct hal_soc *hal_soc);
 void hal_qca8074_attach(struct hal_soc *hal_soc);