dt-bindings: clk: add BCM63268 timer clock definitions

Add missing timer clock definitions for BCM63268.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230322171515.120353-2-noltari@gmail.com


Signed-off-by: Stephen Boyd <sboyd@kernel.org>