ocfs2: Silence gcc warning in ocfs2_write_zero_page().

ocfs2_write_zero_page() has a loop that won't ever be skipped, but gcc
doesn't know that.  Set ret=0 just to make gcc happy.
Signed-off-by: Joel Becker <joel.becker@oracle.com>

fs/ocfs2/file.c

@@ -767,7 +767,7 @@ static int ocfs2_write_zero_page(struct inode *inode, u64 abs_from,
 	struct page *page;
 	unsigned long index = abs_from >> PAGE_CACHE_SHIFT;
 	handle_t *handle = NULL;
-	int ret;
+	int ret = 0;
 	unsigned zero_from, zero_to, block_start, block_end;
 
 	BUG_ON(abs_from >= abs_to);