clk: meson: migrate the audio divider clock to clk_regmap

Rework meson audio divider driver to use clk_regmap and move gxbb
clock using meson_clk_audio_divider to clk_regmap.

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>