drm_hwcomposer: Move hw_module related code out of DrmHwcTwo.* files

... to reduce complexity of DrmHwcTwo class.

Create "hwc2_device" directory that will be later used to fit
all frontend-related code.

Signed-off-by: Roman Stratiienko <roman.o.stratiienko@globallogic.com>
diff --git a/Android.bp b/Android.bp
index 4df2b07..aae6436 100644
--- a/Android.bp
+++ b/Android.bp
@@ -109,6 +109,8 @@
         "backend/BackendClient.cpp",
         "backend/BackendManager.cpp",
         "backend/BackendRCarDu.cpp",
+
+        "hwc2_device/hwc2_device.cpp",
     ],
 }