kvm/ppc/mpic: add KVM_CAP_IRQ_MPIC

Enabling this capability connects the vcpu to the designated in-kernel
MPIC.  Using explicit connections between vcpus and irqchips allows
for flexibility, but the main benefit at the moment is that it
simplifies the code -- KVM doesn't need vm-global state to remember
which MPIC object is associated with this vm, and it doesn't need to
care about ordering between irqchip creation and vcpu creation.

Signed-off-by: Scott Wood <scottwood@freescale.com>
[agraf: add stub functions for kvmppc_mpic_{dis,}connect_vcpu]
Signed-off-by: Alexander Graf <agraf@suse.de>

include/uapi/linux/kvm.h

@@ -667,6 +667,7 @@ struct kvm_ppc_smmu_info {
 #define KVM_CAP_ARM_PSCI 87
 #define KVM_CAP_ARM_SET_DEVICE_ADDR 88
 #define KVM_CAP_DEVICE_CTRL 89
+#define KVM_CAP_IRQ_MPIC 90
 
 #ifdef KVM_CAP_IRQ_ROUTING