dt-bindings: clock: Convert APM XGene clocks to DT schema

dt-bindings: clock: Convert APM XGene clocks to DT schema

Convert the APM XGene clocks to DT schema. The device clock binding is
a bit different from the others, so put it in its own schema file.
Drop the examples.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250521004655.1792703-1-robh@kernel.org
Signed-off-by: Stephen Boyd <sboyd@kernel.org>