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/drmhwctwo.cpp b/drmhwctwo.cpp
index 3d0217c..2dcf088 100644
--- a/drmhwctwo.cpp
+++ b/drmhwctwo.cpp
@@ -150,7 +150,7 @@
   return HWC2::Error::None;
 }
 
-DrmHwcTwo::HwcDisplay::HwcDisplay(DrmResources *drm,
+DrmHwcTwo::HwcDisplay::HwcDisplay(DrmDevice *drm,
                                   std::shared_ptr<Importer> importer,
                                   hwc2_display_t handle, HWC2::DisplayType type)
     : drm_(drm), importer_(importer), handle_(handle), type_(type) {