dts: arm: st: h7rs: Add zephyr,memory-attr to SRAM1 and SRAM2 regions

adds the `zephyr,memory-attr` property to the SRAM1 and SRAM2
memory nodes to explicitly define their MPU attributes as normal
RAM. This ensures proper memory protection and caching behavior
when these regions are used by the kernel or application.

Resolve a Data Access Violation encountered during
test, where the faulting address was 0x30000000.

Note: add the zephyr,memory-attr property in the board overlay for SRAM2
to avoid conflict with the support of h7rs ethernet with MPU regions
enabled.
see link below for more details :
https://github.com/zephyrproject-rtos/zephyr/pull/97364/files#r2439668915

Signed-off-by: Fabrice DJIATSA <[email protected]>

Author: djiatsaf-st

dts/arm/st/h7rs/stm32h7rs.dtsi

@@ -60,6 +60,7 @@
 		reg = <0x30000000 DT_SIZE_K(16)>;
 		compatible = "zephyr,memory-region", "mmio-sram";
 		zephyr,memory-region = "SRAM1";
+		zephyr,memory-attr = <DT_MEM_ARM(ATTR_MPU_RAM)>;
 	};
 
 	/* System data RAM accessible over AHB bus: SRAM2 in D2 domain */

tests/drivers/memc/ram/boards/stm32h7s78_dk.overlay

@@ -0,0 +1,9 @@
+/*
+ * Copyright (c) 2025 STMicroelectronics
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+&sram2 {
+	zephyr,memory-attr = <DT_MEM_ARM(ATTR_MPU_RAM)>;
+};