bootutil: Add better mode selection checks

Improves the mode selection checks to prevent selecting multiple
conflicting modes as has been seen in TFM

Signed-off-by: Jamie McCrae <jamie.mccrae@nordicsemi.no>

boot/bootutil/src/bootutil_priv.h

@@ -58,10 +58,16 @@ struct flash_area;
      defined(MCUBOOT_SWAP_USING_MOVE) + \
      defined(MCUBOOT_DIRECT_XIP) + \
      defined(MCUBOOT_RAM_LOAD) + \
-     defined(MCUBOOT_FIRMWARE_LOADER)) > 1
+     defined(MCUBOOT_FIRMWARE_LOADER) + \
+     defined(MCUBOOT_SWAP_USING_SCRATCH)) > 1
 #error "Please enable only one of MCUBOOT_OVERWRITE_ONLY, MCUBOOT_SWAP_USING_MOVE, MCUBOOT_DIRECT_XIP, MCUBOOT_RAM_LOAD or MCUBOOT_FIRMWARE_LOADER"
 #endif
 
+#if !defined(MCUBOOT_DIRECT_XIP) && \
+     defined(MCUBOOT_DIRECT_XIP_REVERT)
+#error "MCUBOOT_DIRECT_XIP_REVERT cannot be enabled unless MCUBOOT_DIRECT_XIP is used"
+#endif
+
 #if !defined(MCUBOOT_OVERWRITE_ONLY) && \
     !defined(MCUBOOT_SWAP_USING_MOVE) && \
     !defined(MCUBOOT_DIRECT_XIP) && \