Returning an error value in a platform driver's remove callback results in
a generic error message being emitted by the driver core, but otherwise it
doesn't make a difference. The device goes away anyhow.

So instead of triggering the generic platform error message, emit a more
helpful message if a problem occurs and return 0 to suppress the generic
message.

This patch is a preparation for making platform remove callbacks return
void.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Link: https://lore.kernel.org/r/20221014160623.467195-1-u.kleine-koenig@pengutronix.deSigned-off-by: Will Deacon <will@kernel.org>