KVM: arm/arm64: vgic: Drop the kvm_vgic_register_mmio_region()

kvm_vgic_register_mmio_region() was introduced in commit 4493b1c4
("KVM: arm/arm64: vgic-new: Add MMIO handling framework") but never
used, and even never implemented. Remove it to avoid confusing readers.
Reported-by: Haibin Wang <wanghaibin.wang@huawei.com>
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200119090604.398-1-yuzenghui@huawei.com

virt/kvm/arm/vgic/vgic-mmio.h

@@ -98,11 +98,6 @@ extern struct kvm_io_device_ops kvm_io_gic_ops;
 		.uaccess_write = uwr,					\
 	}
 
-int kvm_vgic_register_mmio_region(struct kvm *kvm, struct kvm_vcpu *vcpu,
-				  struct vgic_register_region *reg_desc,
-				  struct vgic_io_device *region,
-				  int nr_irqs, bool offset_private);
-
 unsigned long vgic_data_mmio_bus_to_host(const void *val, unsigned int len);
 
 void vgic_data_host_to_mmio_bus(void *buf, unsigned int len,