ANDROID: KVM: arm64: Mark PAuth as a restricted feature for protected VMs

Protected VMs will only support basic PAuth (FEAT_PAuth). Mark it
as restricted to ensure that later versions aren't supported for
protected guests.

Bug: 278749606
Change-Id: Ie8e2c73f6a7c9a1776ecfefba15892f3721af212
Signed-off-by: Fuad Tabba <tabba@google.com>