ext4: return -ENOMEM instead of success

[ Upstream commit 578620f451f836389424833f1454eeeb2ffc9e9f ]

We should set the error code if kzalloc() fails.

Fixes: 67cf5b09 ("ext4: add the basic function for inline data support")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>