tty: serial: samsung_tty: drop unused argument to irq handlers

The 'irq' argument is not used in any of the callees, we can just drop
it and simplify the code.

No functional changes.

Reviewed-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Signed-off-by: André Draszik <andre.draszik@linaro.org>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20240808-samsung-tty-cleanup-v3-1-494412f49f4b@linaro.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>