drm/i915/gvt: Rename file render.{c, h} to mmio_context.{c, h}

Rename the files to reflect their real role - to switch the mmio context of
each vGPU engine.

v2: update Makefile.
Signed-off-by: NChangbin Du <changbin.du@intel.com>
Signed-off-by: NZhenyu Wang <zhenyuw@linux.intel.com>

drivers/gpu/drm/i915/gvt/Makefile

 GVT_DIR := gvt
 GVT_SOURCE := gvt.o aperture_gm.o handlers.o vgpu.o trace_points.o firmware.o \
 	interrupt.o gtt.o cfg_space.o opregion.o mmio.o display.o edid.o \
-	execlist.o scheduler.o sched_policy.o render.o cmd_parser.o debugfs.o \
+	execlist.o scheduler.o sched_policy.o mmio_context.o cmd_parser.o debugfs.o \
 	fb_decoder.o dmabuf.o
 
 ccflags-y				+= -I$(src) -I$(src)/$(GVT_DIR)

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

@@ -44,7 +44,7 @@
 #include "execlist.h"
 #include "scheduler.h"
 #include "sched_policy.h"
-#include "render.h"
+#include "mmio_context.h"
 #include "cmd_parser.h"
 #include "fb_decoder.h"
 #include "dmabuf.h"