If a platform driver's remove callback returns non-zero the driver core
emits an error message. In such a case however iqs62x_keys_remove()
already issued a (better) message. So return zero to suppress the
generic message.

This patch has no other side effects as platform_remove() ignores the
return value of .remove() after the warning.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230318225110.261439-1-u.kleine-koenig@pengutronix.deSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>