KVM: s390: Replace incorrect atomic_or with atomic_andnot

The offending commit accidentally replaces an atomic_clear with an
atomic_or instead of an atomic_andnot in kvm_s390_vcpu_request_handled.
The symptom is that kvm guests on s390 hang on startup.
This patch simply replaces the incorrect atomic_or with atomic_andnot

Fixes: 805de8f43c (atomic: Replace atomic_{set,clear}_mask() usage)
Signed-off-by: Jason J. Herne <jjherne@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/s390/kvm/kvm-s390.c

@@ -1575,7 +1575,7 @@ static void kvm_s390_vcpu_request(struct kvm_vcpu *vcpu)
 
 static void kvm_s390_vcpu_request_handled(struct kvm_vcpu *vcpu)
 {
-	atomic_or(PROG_REQUEST, &vcpu->arch.sie_block->prog20);
+	atomic_andnot(PROG_REQUEST, &vcpu->arch.sie_block->prog20);
 }
 
 /*