video: fbdev: sh_mobile_lcdcfb: Fix ROP3 sysfs attribute parsing

The ROP3 attribute is expressed as an integer in the 0-255 range. Remove
the wrong conversion to boolean when parsing it.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>