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/drmmode.cpp b/drmmode.cpp
index 081efcd..ee47a8e 100644
--- a/drmmode.cpp
+++ b/drmmode.cpp
@@ -14,8 +14,8 @@
  * limitations under the License.
  */
 
+#include "drmdevice.h"
 #include "drmmode.h"
-#include "drmresources.h"
 
 #include <stdint.h>
 #include <string>