boards: portentah7: allow memory mapping external QSPI flash

This commit enable QSPI flash memory mapping on Arduino Portenta H7

Signed-off-by: Mattia Pennasilico <[email protected]>

Author: pennam

boards/arduino/portenta_h7/arduino_portenta_h7_stm32h747xx_m7.dts

@@ -45,6 +45,14 @@
 		zephyr,memory-region = "SDRAM1";
 		zephyr,memory-attr = <( DT_MEM_ARM(ATTR_MPU_RAM) )>;
 	};
+
+	ext_memory: memory@90000000 {
+		compatible = "zephyr,memory-region";
+		reg = <0x90000000 DT_SIZE_M(16)>; /* max addressable area */
+		zephyr,memory-region = "EXTMEM";
+		/* The ATTR_MPU_EXTMEM attribut causing a MPU FAULT */
+		zephyr,memory-attr = <( DT_MEM_ARM(ATTR_MPU_IO) )>;
+	};
 };
 
 &clk_hse {