remoteproc: k3-dsp: Suppress duplicate error message in .remove()

When the remove callback returns non-zero, the driver core emits an
error message about the error value being ignored. As the driver already
emits an error message already, return zero. This has no effect apart
from suppressing the core's message. The platform device gets unbound
irrespective of the return value.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20231123211657.518181-6-u.kleine-koenig@pengutronix.de
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>