OMAPDSS: DISPC: Fix the usage of wait_for_completion_timeout

The return value of wait_for_completion_timeout() is always
>= 0 with unsigned int type.

So the condition "ret < 0" or "ret >= 0" is pointless.
Signed-off-by: Nliu chuansheng <chuansheng.liu@intel.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/omap2/dss/dispc.c

@@ -3963,9 +3963,6 @@ int omap_dispc_wait_for_irq_timeout(u32 irqmask, unsigned long timeout)
 	if (timeout == 0)
 		return -ETIMEDOUT;
 
-	if (timeout == -ERESTARTSYS)
-		return -ERESTARTSYS;
-
 	return 0;
 }