xen/arm and xen/arm64: implement HYPERVISOR_tmem_op

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

arch/arm64/xen/hypercall.S

@@ -79,6 +79,7 @@ HYPERCALL2(hvm_op);
 HYPERCALL2(memory_op);
 HYPERCALL2(physdev_op);
 HYPERCALL3(vcpu_op);
+HYPERCALL1(tmem_op);
 
 ENTRY(privcmd_call)
 	mov x16, x0