drm_hwcomposer: Wrap libdrm drmMode*{Get|Free}* into RAII

This should elliminate chance of any leaks in the future.
Fix drmModePropertyBlobPtr leak in DrmHwcTwo.cpp.

Signed-off-by: Roman Stratiienko <roman.o.stratiienko@globallogic.com>
diff --git a/drm/DrmConnector.h b/drm/DrmConnector.h
index 3bc18c8..e2789ea 100644
--- a/drm/DrmConnector.h
+++ b/drm/DrmConnector.h
@@ -26,6 +26,7 @@
 #include "DrmEncoder.h"
 #include "DrmMode.h"
 #include "DrmProperty.h"
+#include "DrmUnique.h"
 
 namespace android {
 
@@ -41,7 +42,7 @@
 
   int Init();
   int UpdateEdidProperty();
-  int GetEdidBlob(drmModePropertyBlobPtr &blob);
+  auto GetEdidBlob() -> DrmModePropertyBlobUnique;
 
   uint32_t id() const;