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>