boot: zephyr: prefer swap move if scratch_partition not enabled

With the exception of nrf targets BOOT_SWAP_USING_SCRATCH mode was
still the default algorithm.

Changing the preferred mode in cases where no scratch_partition is
defined will allow successfully building mcuboot for such boards w/o
the need for any board specific overlays.

Signed-off-by: Thomas Stranger <[email protected]>

Author: str4t0m

boot/zephyr/Kconfig

@@ -197,7 +197,7 @@ config BOOT_VALIDATE_SLOT0_ONCE
 config BOOT_PREFER_SWAP_MOVE
 	bool "Prefer the newer swap move algorithm"
 	default y if SOC_FAMILY_NRF
-	default n
+	default y if !$(dt_nodelabel_enabled,scratch_partition)
 	help
 	  If y, the BOOT_IMAGE_UPGRADE_MODE will default to using
 	  "move" instead of "scratch".  This is a separate bool config