drm_hwcomposer: Move DrmHwcTwo.{cpp|h} to hwc2_device/ directory

To keep all frontend-related files in a single directory.

Signed-off-by: Roman Stratiienko <roman.o.stratiienko@globallogic.com>
diff --git a/backend/Backend.h b/backend/Backend.h
index 1a4833e..82b8fca 100644
--- a/backend/Backend.h
+++ b/backend/Backend.h
@@ -17,7 +17,7 @@
 #ifndef ANDROID_BACKEND_H
 #define ANDROID_BACKEND_H
 
-#include "DrmHwcTwo.h"
+#include "hwc2_device/DrmHwcTwo.h"
 
 namespace android {