clk: qcom: gpucc: Add support for GX GDSC for SC7180

Most of the time the CPU should not be touching the GX domain on the
GPU except for a very special use case when the CPU needs to force the
GX headswitch off. Add the GX domain for that use case.  As part of
this add a dummy enable function for the GX gdsc to simulate success
so that the pm_runtime reference counting is correct.  This matches
what was done in sdm845 in commit 85a3d920 ("clk: qcom: Add a
dummy enable function for GX gdsc").

Signed-off-by: Taniya Das <tdas@codeaurora.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lkml.kernel.org/r/1581307266-26989-2-git-send-email-tdas@codeaurora.org


Signed-off-by: Stephen Boyd <sboyd@kernel.org>