[nrf fromlist] drivers: mbox: nrf_vevif_event_tx: Add barrier after event trigger

Due to errata 16 VPR is triggering an event and immediately clears that
event. There are cases when if APP is sleeping it may not be waken up
by that event. Add barrier which fixes the issue (possibly due to
increased period when event is set).

Upstream PR #: 86249

Signed-off-by: Krzysztof Chruściński <[email protected]>

Author: nordic-krch

drivers/mbox/mbox_nrf_vevif_event_tx.c

@@ -40,6 +40,7 @@ static int vevif_event_tx_send(const struct device *dev, uint32_t id, const stru
 	nrf_vpr_csr_vevif_events_trigger(BIT(id));
 
 #if defined(CONFIG_MBOX_NRF_VEVIF_EVENT_USE_54L_ERRATA_16)
+	nrf_barrier_w();
 	while (!nrf_vpr_csr_vevif_events_get()) {
 		;
 	}