ocfs2: potential ERR_PTR dereference on error paths

If "handle" is non null at the end of the function then we assume it's a
valid pointer and pass it to ocfs2_commit_trans();

Signed-off-by: Dan Carpenter <error27@gmail.com>
Cc: <stable@kernel.org>
Signed-off-by: Joel Becker <joel.becker@oracle.com>