MAINTAINERS: add the new dmaengine mailing list

We have a new mailing list hosted by vger for dmaengine
Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

MAINTAINERS

@@ -2718,6 +2718,8 @@ T:	git git://git.linaro.org/people/sumitsemwal/linux-dma-buf.git
 DMA GENERIC OFFLOAD ENGINE SUBSYSTEM
 M:	Vinod Koul <vinod.koul@intel.com>
 M:	Dan Williams <dan.j.williams@intel.com>
+L:	dmaengine@vger.kernel.org
+Q:	https://patchwork.kernel.org/project/linux-dmaengine/list/
 S:	Supported
 F:	drivers/dma/
 F:	include/linux/dma*