msm: kgsl: Don't attempt the LLM/GLM handshake for a640 targets

The LLM/GLM hardware is not used for a640 so don't try to handshake it
following a GMU reset.

Change-Id: Ic0dedbad0d23b88dc9ae7767d6975e9aa7d43e59
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>