[nrf fromtree] platform: nordic_nrf: Configure NRF53 RPMSG NS region

The nRF5340 uses the RPMSG region for communication
between the application and the network core over IPC.
The network core is configured as non secure so in order
to allow communication between the two cores this region
needs to be configured as non secure as well.

This adds the configuration of the region if the partition
manager defined a region for it.

Signed-off-by: Georgios Vasilakis <georgios.vasilakis@nordicsemi.no>
Change-Id: I3821967e83dacbd100fecd9f6afa1b3230910c0d
(cherry picked from commit fae599ed05ba409d17ba5e050b4ff29276150695)

Author: Vge0rge

platform/ext/target/nordic_nrf/common/core/target_cfg_53_91.c

@@ -228,6 +228,17 @@ enum tfm_plat_err_t spu_init_cfg(void)
 				SPU_SECURE_ATTR_NONSECURE, perm, SPU_LOCK_CONF_LOCKED);
 #endif /* REGION_PCD_SRAM_ADDRESS */
 
+#ifdef REGION_RPMSG_NRF53_SRAM_ADDRESS
+	/* Configures rpmsg nrf53 partition to be non-secure */
+	perm = 0;
+	perm |= NRF_SPU_MEM_PERM_READ;
+	perm |= NRF_SPU_MEM_PERM_WRITE;
+
+	spu_regions_sram_config(REGION_RPMSG_NRF53_SRAM_ADDRESS,
+				REGION_RPMSG_NRF53_SRAM_LIMIT,
+				SPU_SECURE_ATTR_NONSECURE, perm, SPU_LOCK_CONF_LOCKED);
+#endif /* REGION_RPMSG_NRF53_SRAM_ADDRESS */
+
 	return TFM_PLAT_ERR_SUCCESS;
 }