msm: kgsl: Add support for coresight

Adding support for Coresight debug bus to work with the GPU,
including registering graphics core with Coresight and a coresight
interface to GPU through sysfs.

Change-Id: I9508659ca7d7d67e8a8becba41d06be76360c570
Signed-off-by: Harsh Vardhan Dwivedi <hdwivedi@codeaurora.org>