FWU: Add return value to fwu_bootloader_mark_image_accepted

When building with SWAP activated,success return value is missing.

Change-Id: Ie00ecf70dc19334758d2d248af3cfc31f6f17f84
Signed-off-by: Michel Jaouen <michel.jaouen@st.com>
diff --git a/secure_fw/partitions/firmware_update/bootloader/mcuboot/tfm_mcuboot_fwu.c b/secure_fw/partitions/firmware_update/bootloader/mcuboot/tfm_mcuboot_fwu.c
index 3260ec2..9ef5338 100644
--- a/secure_fw/partitions/firmware_update/bootloader/mcuboot/tfm_mcuboot_fwu.c
+++ b/secure_fw/partitions/firmware_update/bootloader/mcuboot/tfm_mcuboot_fwu.c
@@ -483,8 +483,8 @@
     }
 #else
     (void)bootloader_image_id;
-    return PSA_SUCCESS;
 #endif
+    return PSA_SUCCESS;
 }
 
 psa_status_t fwu_bootloader_abort(bl_image_id_t bootloader_image_id)