s390x: uv: Tolerate 0x100 query return code

RC 0x100 is not an error but a notice that we could have gotten more
data from the Ultravisor if we had asked for it. So let's tolerate
them in our tests.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Acked-by: Thomas Huth <thuth@redhat.com>