clk: mediatek: add support for parent mux from different source

clk: mediatek: add support for parent mux from different source

There is a current limitation where parents for a mux can be all declared
as they are from a common source. This is not true as there are some MUX
that can have parent from both infracfg or from topckgen.

To handle this, implement a new flag for the mux, CLK_PARENT_MIXED, and
a new entry for the mux parent_flags.

To use this, CLK_PARENT_MIXED must be used and parent_flags will be used
instead of the parent variable.

Entry in parent_flags are just a struct of ID and flags where it will be
defined where that parent comes from with the usage of
CLK_PARENT_INFRASYS or CLK_PARENT_TOPCKGEN.

This permits to have MUX with parents from infracfg or topckgen.

Notice that with CLK_PARENT_MIXED applied the CLK_BYPASS_XTAL is
ignored.
With CLK_PARENT_MIXED declare CLK_PARENT_XTAL for the relevant parent
instead.

Also alias for the CLK_PARENT macro are provided to better clear their
usage. CLK_PARENT_MIXED require these alias that describe the clk type
to be defined in the clk_tree flags to prevent clk ID clash from
different subsystem that may have equal clk ID.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>