boards: st: stm32n6570_dk: re-enable PSRAM cache access

Re-enable the cache usage for the PSRAM now that the PSRAM size
has been adjusted in order to prevent stability issues when using
it with cache enabled.

This reverts the change introduced in
commit 97608e4 ("boards: stm32n6570_dk: Disable cache on PSRAM")

Signed-off-by: Alain Volmat <[email protected]>

Author: Alain Volmat

boards/st/stm32n6570_dk/stm32n6570_dk_common.dtsi

@@ -49,7 +49,7 @@
 		 */
 		reg = <0x90000000 (DT_SIZE_M(32) - 32)>;
 		zephyr,memory-region = "PSRAM";
-		zephyr,memory-attr = <DT_MEM_ARM(ATTR_MPU_RAM_NOCACHE)>;
+		zephyr,memory-attr = <DT_MEM_ARM(ATTR_MPU_RAM)>;
 	};
 
 	leds: leds {