powerpc/kvm: Fix kvmppc_core_pending_dec

The vcpu->arch.pending_exceptions field is a bitfield indexed by
interrupt priority number as returned by kvmppc_book3s_vec2irqprio.
However, kvmppc_core_pending_dec was using an interrupt vector shifted
by 7 as the bit index.  Fix it to use the irqprio value for the
decrementer interrupt instead.  This problem was found by code
inspection.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kvm/book3s.c

@@ -236,7 +236,7 @@ void kvmppc_core_queue_dec(struct kvm_vcpu *vcpu)
 
 int kvmppc_core_pending_dec(struct kvm_vcpu *vcpu)
 {
-	return test_bit(BOOK3S_INTERRUPT_DECREMENTER >> 7, &vcpu->arch.pending_exceptions);
+	return test_bit(BOOK3S_IRQPRIO_DECREMENTER, &vcpu->arch.pending_exceptions);
 }
 
 void kvmppc_core_dequeue_dec(struct kvm_vcpu *vcpu)