[Patch] fs: remove a useless BUG()

[Amerigo Wang <amwang@redhat.com>]

This BUG() is suspicious, it makes its following statements
unreachable, and it seems to be useless, since the caller
of this function already handles the failure properly.
Remove it.

Signed-off-by: WANG Cong <amwang@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: "Theodore Ts'o" <tytso@mit.edu>

---
diff --git a/fs/buffer.c b/fs/buffer.c
index 6fa5302..ac111d7 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1041,7 +1041,6 @@ grow_dev_page(struct block_device *bdev, sector_t block,
 	return page;
 
 failed:
-	BUG();
 	unlock_page(page);
 	page_cache_release(page);
 	return NULL;