The function bcm_qspi_remove() returns zero unconditionally. Make it
return void.

This is a preparation for making platform remove callbacks return void.
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: NFlorian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20221017200143.1426528-1-u.kleine-koenig@pengutronix.deSigned-off-by: NMark Brown <broonie@kernel.org>