Different DRM/KMS backends have a variable set of limitations, which is not always exposed via DRM ioctls.
This implementation of backend-dependent validation provides a register of platform-specific inherited backend class to the map.
The map key is a string that contains the corresponding DRM driver name. During DrmHwcTwo class initialization the vendor.hwc.backend_override system property and driver name will be checked and a backend will be chosen. If the map does not have any backend for the named driver, a generic display backend will be used.
Corresponding to the Issue#34.