qemu: hotplug: Remove code handling possible missing disk source format

qemu media changing code tried to assume old media's format for the new
one if that was not specified. Since the format will always be present
it does not make sense to keep the code around.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>

src/qemu/qemu_hotplug.c

@@ -250,14 +250,9 @@ qemuDomainChangeMediaLegacy(virQEMUDriverPtr driver,
         if (qemuGetDriveSourceString(newsrc, NULL, &sourcestr) < 0)
             goto cleanup;
 
-        if (virStorageSourceGetActualType(newsrc) != VIR_STORAGE_TYPE_DIR) {
-            if (newsrc->format > 0) {
-                format = virStorageFileFormatTypeToString(newsrc->format);
-            } else {
-                if (disk->src->format > 0)
-                    format = virStorageFileFormatTypeToString(disk->src->format);
-            }
-        }
+        if (virStorageSourceGetActualType(newsrc) != VIR_STORAGE_TYPE_DIR)
+            format = virStorageFileFormatTypeToString(newsrc->format);
+
         qemuDomainObjEnterMonitor(driver, vm);
         rc = qemuMonitorChangeMedia(priv->mon,
                                     driveAlias,