msm: kgsl: Make coresight optional

Make coresight support conditional on a new Kconfig option. Support this
by moving the code around a bit and out of the generic headers to make
possible to omit the coresight code when the support isn't available.

This allows us to omit coresight when CONFIG_CORESIGHT isn't enabled
and optionally to remove it at the KGSL level too.

Change-Id: Ic0dedbad2a55df4acf1b8c6e15e5b1b39f08a832
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>