clk: qcom: mmcc-msm8974: remove oxili_ocmemgx_clk

After the internal discussions, it looks like this clock is managed by
RPM itself. Linux kernel should not touch it on its own, as this causes
disagreement with RPM. Shutting down this clock causes the OCMEM<->GPU
interface to stop working, resulting in GPU hangchecks/timeouts.

Fixes: d8b21201 ("clk: qcom: Add support for MSM8974's multimedia clock controller (MMCC)")
Suggested-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Tested-by: Luca Weiss <luca@z3ntu.xyz>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230508153319.2371645-1-dmitry.baryshkov@linaro.org