x86/HVM: don't use confusing/non-suitable XSM checks

x86/HVM: don't use confusing/non-suitable XSM checks

XSM_TARGET checks following rcu_lock_{,live_}remote_domain_by_id() are
rather pointless and potentially confusing. Use XSM_DM_PRIV there
instead.

Note that setting flask_ops.hvm_control to flask_hvm_param() (instead
of introducing flask_hvm_control() is intentional - that function is
already separating the contol and non-control sub-operations.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Acked-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>