s390_pv_perf_clear_reset() is not a very helpful name since that
function needs to be called for a normal and a clear reset via
diag308.

Let's instead name it s390_pv_prep_reset() which reflects the purpose
of the function a bit better.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Message-Id: <20200505124159.24099-1-frankja@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>