drivers: mbox: nrf_vevif_event_rx: fix VPR address

VPR address was obtained from the child instance, however, the child
nodes address is purely an index within the VPR node. The VPR address
needs to be obtained from the parent.

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>

Author: gmarull

drivers/mbox/mbox_nrf_vevif_event_rx.c

@@ -135,7 +135,7 @@ static int vevif_event_rx_init(const struct device *dev)
 		.enabled_mask = 0,                                                                 \
 	};                                                                                         \
 	static const struct mbox_vevif_event_rx_conf conf##inst = {                                \
-		.vpr = (NRF_VPR_Type *)DT_INST_REG_ADDR(inst),                                     \
+		.vpr = (NRF_VPR_Type *)DT_REG_ADDR(DT_INST_PARENT(inst)),                          \
 		.events = DT_INST_PROP(inst, nordic_events),                                       \
 		.events_mask = DT_INST_PROP(inst, nordic_events_mask),                             \
 		.irq_connect = irq_connect##inst,                                                  \