md/bitmap: ensure to load bitmap when creating via sysfs.

When commit 69e51b449d (md/bitmap:  separate out loading a bitmap...)
created bitmap_load, it missed calling it after bitmap_create when a
bitmap is created through the sysfs interface.
So if a bitmap is added this way, we don't allocate memory properly
and can crash.

This is suitable for any -stable release since 2.6.35.
Cc: stable@vger.kernel.org
Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/bitmap.c

@@ -1904,6 +1904,8 @@ location_store(struct mddev *mddev, const char *buf, size_t len)
 			if (mddev->pers) {
 				mddev->pers->quiesce(mddev, 1);
 				rv = bitmap_create(mddev);
+				if (!rv)
+					rv = bitmap_load(mddev);
 				if (rv) {
 					bitmap_destroy(mddev);
 					mddev->bitmap_info.offset = 0;