drm_hwcomposer: Add property that allows disabling of hardware scaling

Set `hwc.drm.scale_with_gpu` property to 1 in case composer hardware
do not have scaling support.

That will force layers that require scaling to be merged by GPU,
and allow other layers to be merged by DRM.

Signed-off-by: Roman Stratiienko <roman.stratiienko@globallogic.com>
diff --git a/drmhwctwo.cpp b/drmhwctwo.cpp
index 5e07f2f..e2c943a 100644
--- a/drmhwctwo.cpp
+++ b/drmhwctwo.cpp
@@ -903,7 +903,9 @@
   for (std::pair<const uint32_t, DrmHwcTwo::HwcLayer *> &l : z_map) {
     if (!HardwareSupportsLayerType(l.second->sf_type()) ||
         !importer_->CanImportBuffer(l.second->buffer()) ||
-        color_transform_hint_ != HAL_COLOR_TRANSFORM_IDENTITY) {
+        color_transform_hint_ != HAL_COLOR_TRANSFORM_IDENTITY ||
+        (l.second->RequireScalingOrPhasing() &&
+         resource_manager_->ForcedScalingWithGpu())) {
       if (client_start < 0)
         client_start = l.first;
       client_size = (l.first - client_start) + 1;