x86/pvh: fix TSC mode setup for PVH Dom0

A PVH Dom0 might use TSC scaling or other HVM specific TSC
adjustments, so only short-circuit the TSC setup for a classic PV
Dom0.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/time.c

@@ -2125,7 +2125,7 @@ void tsc_set_info(struct domain *d,
 {
     ASSERT(!is_system_domain(d));
 
-    if ( is_hardware_domain(d) )
+    if ( is_pv_domain(d) && is_hardware_domain(d) )
     {
         d->arch.vtsc = 0;
         return;