xen: clean up domain mode predicates

There are four operating modes Xen code may find itself running in:
 - native
 - hvm domain
 - pv dom0
 - pv domU

Clean up predicates for testing for these states to make them more consistent.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Xen-devel <xen-devel@lists.xensource.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/drivers/video/xen-fbfront.c b/drivers/video/xen-fbfront.c
index 47ed39b..a463b3d 100644
--- a/drivers/video/xen-fbfront.c
+++ b/drivers/video/xen-fbfront.c
@@ -680,11 +680,11 @@
 
 static int __init xenfb_init(void)
 {
-	if (!is_running_on_xen())
+	if (!xen_domain())
 		return -ENODEV;
 
 	/* Nothing to do if running in dom0. */
-	if (is_initial_xendomain())
+	if (xen_initial_domain())
 		return -ENODEV;
 
 	return xenbus_register_frontend(&xenfb);