scrub: fix uninit return variable in scrub_progress_cycle

Signed-off-by: Chris Mason <clm@fb.com>

cmds-scrub.c

diff --git a/cmds-scrub.c b/cmds-scrub.c
index 4338a0b..3510f57 100644
--- a/cmds-scrub.c
+++ b/cmds-scrub.c
@@ -865,7 +865,7 @@
 /* nb: returns a negative errno via ERR_PTR */
 static void *scrub_progress_cycle(void *ctx)
 {
-	int ret;
+	int ret = 0;
 	int  perr = 0;	/* positive / pthread error returns */
 	int old;
 	int i;