drm_hwcomposer: Rename DrmResources to DrmDevice

DrmDevice is a better name to reflect the fact that DrmResources/
DrmDevice can handle just one dri node.

Suggested here [1] by Sean Paul.
[1] https://lists.freedesktop.org/archives/dri-devel/2018-April/173290.html

Signed-off-by: Alexandru Gheorghe <alexandru-cosmin.gheorghe@arm.com>
diff --git a/drmdisplaycomposition.h b/drmdisplaycomposition.h
index b4c5892..078bf9b 100644
--- a/drmdisplaycomposition.h
+++ b/drmdisplaycomposition.h
@@ -111,8 +111,8 @@
   DrmDisplayComposition(const DrmDisplayComposition &) = delete;
   ~DrmDisplayComposition();
 
-  int Init(DrmResources *drm, DrmCrtc *crtc, Importer *importer,
-           Planner *planner, uint64_t frame_no);
+  int Init(DrmDevice *drm, DrmCrtc *crtc, Importer *importer, Planner *planner,
+           uint64_t frame_no);
 
   int SetLayers(DrmHwcLayer *layers, size_t num_layers, bool geometry_changed);
   int AddPlaneComposition(DrmCompositionPlane plane);
@@ -176,7 +176,7 @@
  private:
   bool validate_composition_type(DrmCompositionType desired);
 
-  DrmResources *drm_ = NULL;
+  DrmDevice *drm_ = NULL;
   DrmCrtc *crtc_ = NULL;
   Importer *importer_ = NULL;
   Planner *planner_ = NULL;