drm_hwcomposer: Make uevent listener standalone

1. DRM event listener doesn't work in this conditions, uevent blocks
   the thread and non-blocking select() doesn't make any sense.
   Remove DRM event handling for now.

2. UEvent listeren is common for all DrmDevices, therefore put it into
   ResourceManager class.

Signed-off-by: Roman Stratiienko <roman.o.stratiienko@globallogic.com>
diff --git a/DrmHwcTwo.h b/DrmHwcTwo.h
index 974c0a8..ed547c0 100644
--- a/DrmHwcTwo.h
+++ b/DrmHwcTwo.h
@@ -359,18 +359,6 @@
     std::string DumpDelta(DrmHwcTwo::HwcDisplay::Stats delta);
   };
 
-  class DrmHotplugHandler : public DrmEventHandler {
-   public:
-    DrmHotplugHandler(DrmHwcTwo *hwc2, DrmDevice *drm)
-        : hwc2_(hwc2), drm_(drm) {
-    }
-    void HandleEvent(uint64_t timestamp_us);
-
-   private:
-    DrmHwcTwo *hwc2_;
-    DrmDevice *drm_;
-  };
-
  private:
   static DrmHwcTwo *toDrmHwcTwo(hwc2_device_t *dev) {
     return static_cast<DrmHwcTwo *>(dev);
@@ -439,6 +427,8 @@
   void HandleDisplayHotplug(hwc2_display_t displayid, int state);
   void HandleInitialHotplugState(DrmDevice *drmDevice);
 
+  void HandleHotplugUEvent();
+
   ResourceManager resource_manager_;
   std::map<hwc2_display_t, HwcDisplay> displays_;