dw_mci_pltfm_remove() returned zero unconditionally. Make it return void
instead which makes its semantics a bit clearer.

Convert the drivers that use this function as .remove() callback to
.remove_new() which has the right prototype. This helps getting rid of
the platform_driver's remove callback that returns an int (which is
error prone). The other users didn't check the return value anyhow.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230505221506.1247424-1-u.kleine-koenig@pengutronix.deSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>