Remove unused variable.

Submitted by:	ganbold

sys/dev/ata/ata-all.c

@@ -304,11 +304,10 @@ ata_suspend(device_t dev)
 int
 ata_resume(device_t dev)
 {
-    struct ata_channel *ch;
     int error;
 
     /* check for valid device */
-    if (!dev || !(ch = device_get_softc(dev)))
+    if (!dev || !device_get_softc(dev))
 	return ENXIO;
 
     /* reinit the devices, we dont know what mode/state they are in */