dt-bindings: clock: adi,axi-clkgen: add clock-output-names property

dt-bindings: clock: adi,axi-clkgen: add clock-output-names property

Add an optional `clock-output-names` property to the ADI AXI Clock
Generator binding. This is already being used in the Linux driver and
real-world dtbs, so we should document it to allow for correct binding
validation.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/20250811-dt-bindings-clk-axi-clkgen-add-clock-output-names-property-v1-1-f02727736aa7@baylibre.com
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>