video: fbdev: uvesafb: fix "noblank" option handling

Fix the recent regression.

Fixes: dbc7ece1 ("video: uvesafb: use true,false for bool variables")
Cc: Jason Yan <yanaijie@huawei.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/81c9f140-d6fb-803a-18c8-04dae1007ab3@samsung.com