ARM: dts: msm: Replace gdsc_hlos1_vote_gpu_smmu with gdsc_gpu_cx

We use gdsc_gpu_cx for graphics votes on the CX rail for msmcobalt
instead of gdsc_hlos1_vote_gpu_smmu for. Make this change and
remove the redundant gdsc from the device tree.

Change-Id: I5039ac516d7de6776cfa1038fdd8a1160a5f80db
Signed-off-by: Devesh Jhunjhunwala <deveshj@codeaurora.org>