binderfs: fix error return code in binderfs_fill_super()

Fix to return a negative error code -ENOMEM from the new_inode() and
d_make_root() error handling cases instead of 0, as done elsewhere in
this function.

Fixes: 849d540d ("binderfs: implement "max" mount option")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Christian Brauner <christian@brauner.io>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>