qcacmn: Flush reg write work before bus suspend

Delayed register write work needs to be flushed before bus suspend to
make sure there are on pending writes after driver's bus suspend routine
exits. In case delayed work context is not able to finish before the bus
(PCI) is suspended (DRV), it may lead to a NOC error.

Change-Id: I40cbcec5d23ddd75ec87aed69ac45d95510fa880
CRs-Fixed: 2813733

dp/wifi3.0/dp_main.c

@@ -11525,6 +11525,8 @@ static QDF_STATUS dp_bus_suspend(struct cdp_soc_t *soc_hdl, uint8_t pdev_id)
 		dp_service_mon_rings(soc, DP_MON_REAP_BUDGET);
 	}
 
+	hal_flush_reg_write_work(soc->hal_soc);
+
 	return QDF_STATUS_SUCCESS;
 }