ARM: dts: msm: Add OPP table entries for gpu clocks on sdm670

Add opp-handle entries for graphics clocks in graphics CC nodes.
These entries trigger clock driver to populate OPP table for
given graphics node 'dev' with corresponding clk frequencies.

Change-Id: If79e7efa265a41aefe2e5010aadc8eb6d4c1a39c
Signed-off-by: Odelu Kukatla <okukatla@codeaurora.org>