clk: qcom: gcc-sdm845: get rid of the test clock

The test clock isn't in the bindings and apparently it's not used by
anyone upstream.  Remove it.

Suggested-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20210409183004.1617777-4-dmitry.baryshkov@linaro.org
Signed-off-by: Stephen Boyd <sboyd@kernel.org>