KVM: arm64: Eagerly init vgic dist/redist on vgic creation

In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Eagerly init vgic dist/redist on vgic creation If vgic_allocate_private_irqs_locked() fails for any odd reason, we exit kvm_vgic_create() early, leaving dist->rd_regions uninitialised. kvm_vgic_dist_destroy() then comes along and walks into the weeds trying to free the RDs. Got to love this stuff. Solve it by moving all the static initialisation early, and make sure that if we fail halfway, we're in a reasonable shape to perform the rest of the teardown. While at it, reset the vgic model on failure, just in case...