i915/gvt: remove unused xen bits

No Xen support anywhere here.  Remove a dead declaration and an unused
include.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20200404094101.672954-4-hch@lst.de

drivers/gpu/drm/i915/gvt/gvt.c

@@ -31,7 +31,6 @@
  */
 
 #include <linux/types.h>
-#include <xen/xen.h>
 #include <linux/kthread.h>
 
 #include "i915_drv.h"

drivers/gpu/drm/i915/gvt/hypercall.h

@@ -79,6 +79,4 @@ struct intel_gvt_mpt {
 	bool (*is_valid_gfn)(unsigned long handle, unsigned long gfn);
 };
 
-extern struct intel_gvt_mpt xengt_mpt;
-
 #endif /* _GVT_HYPERCALL_H_ */