UBI: fix checkpatch.pl errors and warnings

Just out or curiousity ran checkpatch.pl for whole UBI,
and discovered there are quite a few of stylistic issues.
Fix them.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/drivers/mtd/ubi/gluebi.c b/drivers/mtd/ubi/gluebi.c
index 49f52dc..605812b 100644
--- a/drivers/mtd/ubi/gluebi.c
+++ b/drivers/mtd/ubi/gluebi.c
@@ -249,8 +249,8 @@
 	if (err)
 		goto out_err;
 
-        instr->state = MTD_ERASE_DONE;
-        mtd_erase_callback(instr);
+	instr->state = MTD_ERASE_DONE;
+	mtd_erase_callback(instr);
 	return 0;
 
 out_err: