media: xilinx: dma: stop_streaming should return void

Fix our driver to follow change in mainline code.
Based on mainline patch:
"[media] vb2: stop_streaming should return void"
(sha1: e37559b22c63b557d242bfa1a07ab1b8f7d5d9f1)

Warning log:
drivers/media/platform/xilinx/xilinx-dma.c:505:2: warning:
initialization from incompatible pointer type [enabled by default]
  .stop_streaming = xvip_dma_stop_streaming,
  ^
drivers/media/platform/xilinx/xilinx-dma.c:505:2: warning: (near
initialization for 'xvip_dma_queue_qops.stop_streaming') [enabled by
default]

Reported-by: Wendy Liang <wendy.liang@xilinx.com>
Acked-by: Christian Kohn <christian.kohn@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
ARM: zynq_defconfig: Enable VDMA

Signed-off-by: Christian Kohn <christian.kohn@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
ARM: zynq: Leave CMA size at default

Setting the default size for the CMA to high breaks platform that don't
have enough memory to satisfy the CMA demand. Leaving it at default
should enable more platforms to get a working base line using the
defconfig.

Reported-by: Stephen MacMahon <stephenm@xilinx.com>
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>