drm_hwcomposer: Tidy-up DrmPlane class

This allow to throw away few lines from DrmDevice::Init() making it less
complicated.

Signed-off-by: Roman Stratiienko <roman.o.stratiienko@globallogic.com>
diff --git a/compositor/Planner.cpp b/compositor/Planner.cpp
index f43e314..24b43ba 100644
--- a/compositor/Planner.cpp
+++ b/compositor/Planner.cpp
@@ -31,10 +31,10 @@
   std::vector<DrmPlane *> usable_planes;
   std::copy_if(primary_planes->begin(), primary_planes->end(),
                std::back_inserter(usable_planes),
-               [=](DrmPlane *plane) { return plane->GetCrtcSupported(*crtc); });
+               [=](DrmPlane *plane) { return plane->IsCrtcSupported(*crtc); });
   std::copy_if(overlay_planes->begin(), overlay_planes->end(),
                std::back_inserter(usable_planes),
-               [=](DrmPlane *plane) { return plane->GetCrtcSupported(*crtc); });
+               [=](DrmPlane *plane) { return plane->IsCrtcSupported(*crtc); });
   return usable_planes;
 }