ARM: dts: msm: Update GPU power levels for atoll

GPU 180Mhz and 267Mhz clock falls to same voltage
(Low SVS) corner. There is no power benefit to having
the GPU 180Mhz. Hence remove the GPU 180Mhz clock from
the existing power levels plan.

Change-Id: I0f16debfb7f9e9c838e618a95daef0c6b3e47264
Signed-off-by: Hareesh Gundu <hareeshg@codeaurora.org>