KVM: PPC: Move xics_debugfs_init out of create

As we are about to hold the kvm->lock during the create operation on KVM
devices, we should move the call to xics_debugfs_init into its own
function, since holding a mutex over extended amounts of time might not
be a good idea.

Introduce an init operation on the kvm_device_ops struct which cannot
fail and call this, if configured, after the device has been created.

Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

include/linux/kvm_host.h

@@ -1115,6 +1115,12 @@ struct kvm_device_ops {
 	const char *name;
 	int (*create)(struct kvm_device *dev, u32 type);
 
+	/*
+	 * init is called after create if create is successful and is called
+	 * outside of holding kvm->lock.
+	 */
+	void (*init)(struct kvm_device *dev);
+
 	/*
 	 * Destroy is responsible for freeing dev.
 	 *