vfs/idmapped_mounts.c: Change mount_setattr expected output

vfs/idmapped_mounts.c: Change mount_setattr expected output

In kernel commit dacfd001eaf2 (“fs/mnt_idmapping.c: Return -EINVAL
when no map is written”), the behavior of mount_setattr changed to
return EINVAL when attempting to create an idmapped mount when using
a user namespace with no mappings. The following commit updates the test
to expect no mount to be created in that case. And since no mount is created,
this commit also removes the check for overflow IDs because it does not make
sense to check for overflow IDs for a mount that was not created.

Signed-off-by: Taylor Jackson <tjackson9431@gmail.com>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Zorro Lang <zlang@kernel.org>