bootutil: Avoid re-definition of MCUBOOT_SWAP_USING_SCRATCH

Two identical definitions of MCUBOOT_SWAP_USING_SCRATCH occur in
bootutil_priv.h and bootutil_area.c. This commit removes the duplicate in
bootutil_area.c.

Signed-off-by: kkrentz <konrad.krentz@gmail.com>

Author: kkrentz

boot/bootutil/src/bootutil_area.c

@@ -5,6 +5,7 @@
  * Copyright (c) 2016-2019 JUUL Labs
  * Copyright (c) 2019-2020 Arm Limited
  * Copyright (c) 2025 Nordic Semiconductor ASA
+ * Copyright (c) 2025 Siemens AG
  *
  * Original license:
  *
@@ -27,6 +28,7 @@
  */
 
 #include "bootutil_area.h"
+#include "bootutil_priv.h"
 #include "bootutil/image.h"
 #include "bootutil/bootutil_public.h"
 #ifdef MCUBOOT_ENC_IMAGES
@@ -36,16 +38,6 @@
 
 BOOT_LOG_MODULE_DECLARE(mcuboot);
 
-#if !defined(MCUBOOT_OVERWRITE_ONLY) && \
-    !defined(MCUBOOT_SWAP_USING_MOVE) && \
-    !defined(MCUBOOT_SWAP_USING_OFFSET) && \
-    !defined(MCUBOOT_DIRECT_XIP) && \
-    !defined(MCUBOOT_RAM_LOAD) && \
-    !defined(MCUBOOT_SINGLE_APPLICATION_SLOT) && \
-    !defined(MCUBOOT_FIRMWARE_LOADER)
-#define MCUBOOT_SWAP_USING_SCRATCH 1
-#endif
-
 /**
  * Amount of space used to save information required when doing a swap,
  * or while a swap is under progress, but not the status of sector swap