omap: gpu: remove sysfs interface.
We use a modified PVR-SOURCE, but this driver was moved into CM sources, so we cannot commit the change here. The common OMAP SGX sysfs interface originally provides read-only entries. These entries are getting modified for rw access which allows us to dynamically overclock the GPU frequency. Trickster Mod supports this interface for GPU settings change and we can use modified frequency_limit entry for OC.