dt-bindings: clock: si5351: convert to yaml

dt-bindings: clock: si5351: convert to yaml

The following additional properties are described:

  - clock-names
  - clock-frequency of the clkout child nodes

In order to suppress warnings from the DT schema validator, the clkout
child nodes are prescribed names clkout@[0-7] rather than clkout[0-7].

The example is refined as follows:

  - correct the usage of property pll-master -> silabs,pll-master
  - give an example of how the silabs,pll-reset property can be used

I made myself maintainer of the file as I cannot presume that anybody
else wants the responsibility.

Cc: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Cc: Rabeeh Khoury <rabeeh@solid-run.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Link: https://lore.kernel.org/r/20231124-alvin-clk-si5351-no-pll-reset-v6-1-69b82311cb90@bang-olufsen.dk
Signed-off-by: Stephen Boyd <sboyd@kernel.org>