clk: qcom: Avoid SMMU/cx gdsc corner cases

Mark the msm8998 cpu CX gdsc as votable and use the hw control to avoid
corner cases with SMMU per hardware documentation.

Fixes: 3f7df5ba

 ("clk: qcom: Add MSM8998 GPU Clock Controller (GPUCC) driver")
Signed-off-by: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
Link: https://lkml.kernel.org/r/20191217171905.5619-1-jeffrey.l.hugo@gmail.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>