hostfs: Freeing an ERR_PTR in hostfs_fill_sb_common()

commit 8a545f185145e3c09348cd74326268ecfc6715a3 upstream.

We can't pass error pointers to kfree() or it causes an oops.

Fixes: 52b209f7 ('get rid of hostfs_read_inode()')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>