xsm: Add missing access checks

xsm: Add missing access checks

Actions requiring IS_PRIV should also require some XSM access control
in order for XSM to be useful in confining multiple privileged
domains. Add XSM hooks for new hypercalls and sub-commands that are
under IS_PRIV but not currently under any access checks.

Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>