dmaengine: remove ste_dma40 from issue_pending TODO

ste_dma40 now implements issue_pending according to documentation.
Submit adds descriptos to a pending queue with are flushed down to the DMAC
at issue_pending.
Signed-off-by: Per Forlin <per.forlin@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/TODO

@@ -9,6 +9,5 @@ TODO for slave dma
 	- mxs-dma.c
 	- dw_dmac
 	- intel_mid_dma
-	- ste_dma40
 4. Check other subsystems for dma drivers and merge/move to dmaengine
 5. Remove dma_slave_config's dma direction.