boot: zephyr: socs: add overlay & conf for stm32h573xx_ext_flash_app

Following the introduction of stm32h573i-dk 'ext_flash_app' board variant,
for storing apps in external flash and chainloading them with MCUboot that's
placed in internal flash, we need a devicetree overlay to designate the
internal flash and flash controller as the chosen 'zephyr,flash'
and 'zephyr,flash-controller' for the MCUboot zephyr application.

Also, BOOT_MAX_IMG_SECTORS_AUTO is no longer needed to be disabled after
including the 'soc-nv-flash' binding in the 'st,stm32-xspi-nor' binding,
then adding the 'erase-block-size' and 'write-block-size' properties
in external Flash DT node.

Signed-off-by: Tim Pambor <[email protected]>

fix

Author: tpambor

boot/zephyr/boards/stm32h573i_dk.conf

@@ -0,0 +1 @@
+CONFIG_STM32_MEMMAP=y

boot/zephyr/socs/stm32h573xx_ext_flash_app.conf

@@ -0,0 +1,7 @@
+/ {
+	chosen {
+		zephyr,flash = &flash0;
+		zephyr,flash-controller = &flash;
+		zephyr,code-partition = &boot_partition;
+	};
+};