KVM: arm64: Monitor Debug support for non-protected guests

Add monitor debug support for non-protected guests in protected
mode.

Save and restore the monitor debug state when running a
non-protected guest, and propagate the monitor debug
configuration of non-protected vcpus from the host.

This patch assumes that the hyp vcpu debug iflags are kept in
sync with the host.

Signed-off-by: Fuad Tabba <tabba@google.com>