dt-bindings: rng: omap_rng: Drop requirement for clocks

For K3 devices the clock fed into the RNG module is shared with the rest
of the Crypto module, it is not dedicated to the RNG module and cannot be
controlled by the RNG driver. The driver does not require this clock to
always be defined and the DT binding should not force it either.

Remove this so we can start dropping out the clock properties as needed.

Signed-off-by: Andrew Davis <afd@ti.com>
Link: https://lore.kernel.org/r/20220901171041.32056-1-afd@ti.com


Signed-off-by: Rob Herring <robh@kernel.org>