ipack: Handle a driver without remove callback

ipack: Handle a driver without remove callback

A driver that only consumes devm-managed resources might well have no
remove callback. Additionally given that the device core ignores the return
value of ipack_bus_remove() stop returning an error code.

Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
Acked-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Link: https://lore.kernel.org/r/20210207215556.96371-2-uwe@kleine-koenig.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>