drm/i915/gvt: make mpt.h self-contained

Add necessary #includes	and forward declarations to make the header
compile on its own.
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/73958c4ed1d94aa581acd91f7d7e82785b13d07e.1607422863.git.jani.nikula@intel.com

drivers/gpu/drm/i915/Makefile

@@ -283,8 +283,7 @@ obj-$(CONFIG_DRM_I915_GVT_KVMGT) += gvt/kvmgt.o
 
 # exclude some broken headers from the test coverage
 no-header-test := \
-	display/intel_vbt_defs.h \
-	gvt/mpt.h
+	display/intel_vbt_defs.h
 
 extra-$(CONFIG_DRM_I915_WERROR) += \
 	$(patsubst %.h,%.hdrtest, $(filter-out $(no-header-test), \

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

@@ -33,6 +33,8 @@
 #ifndef _GVT_MPT_H_
 #define _GVT_MPT_H_
 
+#include "gvt.h"
+
 /**
  * DOC: Hypervisor Service APIs for GVT-g Core Logic
  *