msm: kgsl: Move ringbuffer global allocations to init time

With eCP, kgsl will not be allocating these buffers or anything
related to the ringbuffers. Move this to init time so that this
only gets called when eCP is disabled.

Change-Id: I3c492581d904e35e4a58931bdd1f6e83546a3d2c
Signed-off-by: Harshdeep Dhatt <hdhatt@codeaurora.org>