xen: Include xen/page.h rather than asm/xen/page.h

Using xen/page.h will be necessary later for using common xen page
helpers.

As xen/page.h already include asm/xen/page.h, always use the later.

Signed-off-by: Julien Grall <julien.grall@citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: netdev@vger.kernel.org
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
index 9e6a851..d10effe 100644
--- a/drivers/xen/manage.c
+++ b/drivers/xen/manage.c
@@ -19,10 +19,10 @@
 #include <xen/grant_table.h>
 #include <xen/events.h>
 #include <xen/hvc-console.h>
+#include <xen/page.h>
 #include <xen/xen-ops.h>
 
 #include <asm/xen/hypercall.h>
-#include <asm/xen/page.h>
 #include <asm/xen/hypervisor.h>
 
 enum shutdown_state {