drm/imx/dcss: Drop if blocks with always false condition

dcss_drv_platform_remove() is only called for a device after
dcss_drv_platform_probe() returned 0. In that case dev_set_drvdata() was
called with a non-NULL value and so dev_get_drvdata() won't return NULL.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Laurentiu Palcu <laurentiu.palcu@oss.nxp.com>
Signed-off-by: Laurentiu Palcu <laurentiu.palcu@oss.nxp.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221230130025.240776-1-u.kleine-koenig@pengutronix.de