clk: meson: introduce meson-clkc-utils

Let's introduce a new module called meson-clkc-utils that
will contain shared utility functions for all Amlogic clock
controller drivers.

The first utility function is a replacement of of_clk_hw_onecell_get
in order to get rid of the NR_CLKS define in all Amlogic clock
drivers.

The goal is to move all duplicate probe and init code in this module.

[jbrunet: Fixed MODULE_LICENCE checkpatch warning]
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20230607-topic-amlogic-upstream-clkid-public-migration-v2-1-38172d17c27a@linaro.org
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>