Remove pointless cast-as-lvalue usage from modedb.c

It's evil, people. Don't use that particular gcc extension.
I've yet to meet anybody who could read the resulting code
and tell me what the heck it does.

drivers/video/modedb.c

@@ -583,7 +583,7 @@ void fb_var_to_videomode(struct fb_videomode *mode,
 {
 	u32 pixclock, hfreq, htotal, vtotal;
 
-	(char *) mode->name = NULL;
+	mode->name = NULL;
 	mode->xres = var->xres;
 	mode->yres = var->yres;
 	mode->pixclock = var->pixclock;