selftests: KVM: s390: fixup fprintf format error in reset.c

value is u64 and not string.

Reported-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 file changed