[nrf noup] booutil: loader: Fixup for NSIB and multi-image

Commit 8fe7070 broke bootloader updates
for nRF91 and non-multi image builds. This commit is fixing this by
restoring the previous functionality and `ifdef` out the new logic
needed for multi-image.

Ref. NCSDK-23305

Signed-off-by: Sigvart Hovland <[email protected]>
(cherry picked from commit 7429a98)
Signed-off-by: Dominik Ermel <[email protected]>
(cherry picked from commit 8c5b560)
(cherry picked from commit 745cf4e)
Signed-off-by: Dominik Ermel <[email protected]>

boot/bootutil/src/loader.c

@@ -967,7 +967,6 @@ boot_validated_swap_type(struct boot_loader_state *state,
         if(reset_addr < PM_CPUNET_B0N_ADDRESS)
 #endif
         {
-            const struct flash_area *nsib_fa;
             const struct flash_area *primary_fa;
             rc = flash_area_open(flash_area_id_from_multi_image_slot(
                                  BOOT_CURR_IMG(state), BOOT_PRIMARY_SLOT),
@@ -978,6 +977,9 @@ boot_validated_swap_type(struct boot_loader_state *state,
 
             /* Check start and end of primary slot for current image */
             if (reset_addr < primary_fa->fa_off) {
+#if defined(CONFIG_SOC_NRF5340_CPUAPP) && defined(CONFIG_NRF53_MULTI_IMAGE_UPDATE)
+		    const struct flash_area *nsib_fa;
+
                     /* NSIB upgrade slot */
                     rc = flash_area_open((uint32_t)_image_1_primary_slot_id,
                                     &nsib_fa);
@@ -992,6 +994,10 @@ boot_validated_swap_type(struct boot_loader_state *state,
                         /* Set primary to be NSIB upgrade slot */
                         BOOT_IMG_AREA(state, 0) = nsib_fa;
                     }
+#else
+                return BOOT_SWAP_TYPE_NONE;
+#endif
+
             } else if (reset_addr > (primary_fa->fa_off + primary_fa->fa_size)) {
                 /* The image in the secondary slot is not intended for any */
                 return BOOT_SWAP_TYPE_NONE;