clk: meson: axg-audio: migrate to the new parent description method

This clock controller use the string comparison method to describe parent
relation between the clocks, which is not optimized. A recent patch [0]
allows parents to be specified without string names or with device-tree
clock name by using a new assignment structure.

Migrate to the new way by using .parent_hws where possible (when parent
clocks are localy declared in the controller) and use .parent_data
otherwise.

Remove clk input helper and all bypass clocks (declared in probe function)
which are no longer used since we are able to use device-tree clock name
directly.

[0] commit fc0c209c

 ("clk: Allow parents to be specified without string names")

Signed-off-by: Alexandre Mergnat <amergnat@baylibre.com>
[jbrunet@baylibre.com: remove CLK_SET_RATE_PARENT from mst muxes]
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>