The IRQ line might not be connected on some boards. Allow the driver
to be probed without it.
Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Link: https://patch.msgid.link/20240708084107.38986-5-frieder@fris.deSigned-off-by: Mark Brown <broonie@kernel.org>