msm: kgsl: Add GPU CX Ipeak client support

To handle CX peak current limit, GPU needs to call CX Ipeak driver APIs
when it switches between threshold points.

CX Ipeak driver will throttle cDSP frequency if all the clients are
running at their respective threshold frequencies to limit CX peak
current.

Change-Id: I5e53b8f4b5c3d83508249e223e8220ec5831c8fd
Signed-off-by: Deepak Kumar <dkumar@codeaurora.org>