clk: msm: clock-gpu-cobalt: Update the graphics core clock frequency

clk: msm: clock-gpu-cobalt: Update the graphics core clock frequency

Remove support for 710 MHz as the highest possible frequency that
the graphics core clock can scale to on MSMCOBALT v2. The new FMAX
will be 670 MHz.

CRs-Fixed: 1072272
Change-Id: I39119c9dd527dec6a9f4745c0502c83d083f4b26
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>