clk: qcom: gcc-sc8180x: use ARRAY_SIZE instead of specifying num_parents

Use ARRAY_SIZE() instead of manually specifying num_parents. This makes
adding/removing entries to/from parent_data easy and errorproof.
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20210405224743.590029-31-dmitry.baryshkov@linaro.orgSigned-off-by: Stephen Boyd <sboyd@kernel.org>