boards/stm32f769i_disco: add accessible memory region for QSPI flash

By default, the QSPI region is marked as EXTMEM and inaccessible
(see #57467), mark the first 64MB as IO on stm32f769i_disco.

Signed-off-by: Armin Brauns <[email protected]>

Author: arbrauns

boards/st/stm32f769i_disco/stm32f769i_disco.dts

@@ -79,6 +79,13 @@
 		sw0 = &user_button;
 		spi-flash0 = &mx25l51245g;
 	};
+
+	quadspi_memory_avail: memory-avail@90000000 {
+		compatible = "zephyr,memory-region", "mmio-sram";
+		reg = <0x90000000 DT_SIZE_M(64)>;
+		zephyr,memory-region = "QSPI_AVAIL";
+		zephyr,memory-attr = <( DT_MEM_ARM(ATTR_MPU_IO) )>;
+	};
 };
 
 &clk_hse {

dts/arm/st/f7/stm32f7.dtsi

@@ -45,10 +45,10 @@
 		};
 	};
 
-	quadspi_memory: memory@90000000 {
+	quadspi_memory: memory-placeholder@90000000 {
 		compatible = "zephyr,memory-region", "mmio-sram";
 		reg = <0x90000000 DT_SIZE_M(256)>;
-		zephyr,memory-region = "QSPI";
+		zephyr,memory-region = "QSPI_PLACEHOLDER";
 		zephyr,memory-attr = <( DT_MEM_ARM(ATTR_MPU_EXTMEM) )>;
 	};