drm/ssd130x: Make ssd130x_remove() return void

drm/ssd130x: Make ssd130x_remove() return void

This function returns zero unconditionally, so there isn't any benefit
of returning a value. Make it return void to be able to see at a glance
that the return value of ssd130x_i2c_remove() is always zero.

This patch is a preparation for making i2c remove callbacks return void.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220425192306.59800-1-u.kleine-koenig@pengutronix.de