storage_util: Split backing_fmt set in storageBackendCreateQemuImgOpts

The only way backing_fmts could be set is if the info->format was
not RAW (see storageBackendCreateQemuImgSetBacking), so let's just
extract it from the if/else surrounding the application of the
encryption options.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>

src/storage/storage_util.c

@@ -822,12 +822,13 @@ storageBackendCreateQemuImgOpts(virStorageEncryptionInfoDefPtr enc,
 {
     virBuffer buf = VIR_BUFFER_INITIALIZER;
 
-    if (info.format == VIR_STORAGE_FILE_RAW && enc) {
-        virQEMUBuildQemuImgKeySecretOpts(&buf, enc, info.secretAlias);
-    } else {
     if (info.backingPath)
         virBufferAsprintf(&buf, "backing_fmt=%s,",
                           virStorageFileFormatTypeToString(info.backingFormat));
+
+    if (info.format == VIR_STORAGE_FILE_RAW && enc) {
+        virQEMUBuildQemuImgKeySecretOpts(&buf, enc, info.secretAlias);
+    } else {
         if (info.encryption)
             virBufferAddLit(&buf, "encryption=on,");
         if (info.preallocate) {