block: Add missing bdrv_delete() for SG_IO BlockDriver in find_image_format()

This patch adds a missing bdrv_delete() call in find_image_format() so that a
SG_IO BlockDriver properly releases the temporary BlockDriverState *bs created
from bdrv_file_open()

Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
Reported-by: Chris Krumme <chris.krumme@windriver.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/block.c b/block.c
index 24c63f6..296de89 100644
--- a/block.c
+++ b/block.c
@@ -332,8 +332,10 @@
         return NULL;
 
     /* Return the raw BlockDriver * to scsi-generic devices */
-    if (bs->sg)
+    if (bs->sg) {
+        bdrv_delete(bs);
         return bdrv_find_format("raw");
+    }
 
     ret = bdrv_pread(bs, 0, buf, sizeof(buf));
     bdrv_delete(bs);