backend-drm: Use dumb buffer for cursor buffer
Fixes: #375
Currently the DRM-backend depends on GBM for cursor planes, more specifically for the buffers for cursor planes. This means that cursor planes can be used only if GBM is initialized, which means using GL-renderer. Hence when using Pixman-renderer, cursor plane is not used.
This changes adds support to use dumb buffer as cursor buffer for cursor plane and allow it to be used with both pixman and gl renderer.This also avoids the cost of repainting for only cursor motion with pixman renderer.
GBM path is completely removed for cursor related stuff.
Signed-off-by: Veeresh Kadasani veeresh.kadasani@huawei.com