ipack: Fail earlier for drivers without probe function

A driver without a probe function isn't useful as it can never be used.
Let registering such a driver fail already instead of failing every
binding.

This is only cosmetic as there is no ipack driver without a probe function.

Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
Acked-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Link: https://lore.kernel.org/r/20210207215556.96371-1-uwe@kleine-koenig.org


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