While gs101 needs exactly two clocks for the UART, the schema doesn't
currently limit the maximum number to this and instead the default of
five from this schema is applied.

Update the schema accordingly.
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: André Draszik <andre.draszik@linaro.org>
Link: https://lore.kernel.org/r/20240725-gs101-uart-binding-v5-2-e237be8253a9@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>