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

hal/wifi3.0/hal_api.h

@@ -2611,4 +2611,16 @@ static inline QDF_STATUS hal_construct_shadow_regs(void *hal_soc)
 	return QDF_STATUS_SUCCESS;
 }
 #endif /* GENERIC_SHADOW_REGISTER_ACCESS_ENABLE */
+
+#ifdef FEATURE_HAL_DELAYED_REG_WRITE
+/**
+ * hal_flush_reg_write_work() - flush all writes from register write queue
+ * @arg: hal_soc pointer
+ *
+ * Return: None
+ */
+void hal_flush_reg_write_work(hal_soc_handle_t hal_handle);
+#else
+static inline void hal_flush_reg_write_work(hal_soc_handle_t hal_handle) { }
+#endif
 #endif /* _HAL_APIH_ */