dmaengine: ioat - fix spare sparse complain

>> drivers/dma/ioat/dma_v3.c:371:6: sparse: symbol 'ioat3_timer_event' was not declared.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Acked-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/ioat/dma_v3.c

@@ -368,7 +368,7 @@ static void check_active(struct ioat2_dma_chan *ioat)
 
 }
 
-void ioat3_timer_event(unsigned long data)
+static void ioat3_timer_event(unsigned long data)
 {
 	struct ioat2_dma_chan *ioat = to_ioat2_chan((void *) data);
 	struct ioat_chan_common *chan = &ioat->base;