KVM: ARM: Move all vcpu init code into kvm_arch_vcpu_create()

Fold init() into create() now that the two are called back-to-back by
common KVM code (kvm_vcpu_init() calls kvm_arch_vcpu_init() as its last
action, and kvm_vm_ioctl_create_vcpu() calls kvm_arch_vcpu_create()
immediately thereafter).  This paves the way for removing
kvm_arch_vcpu_{un}init() entirely.

Note, there is no associated unwinding in kvm_arch_vcpu_uninit() that
needs to be relocated (to kvm_arch_vcpu_destroy()).

No functional change intended.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>