dt-bindings: clocks: qcom,gcc-msm8998: Reflect actually referenced clks

dt-bindings: clocks: qcom,gcc-msm8998: Reflect actually referenced clks

Some of these clocks are not referenced by the driver at all whereas
aud_ref_clk and core_bi_pll_test_se are but were missing from the
bindings.  These clocks are optional (and not currently provided
anywhere) while "xo" and "sleep_clk" are mandatory.

Note that none of these clocks were used beforehand as the driver
referenced them by their global name.

Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Link: https://lore.kernel.org/r/20210911121340.261920-7-marijn.suijten@somainline.org
Signed-off-by: Stephen Boyd <sboyd@kernel.org>