dmaengine: xilinx_dma: Fix SG capability check for MCDMA

The SG capability is inherently present with Multichannel DMA operation.
The register used to check for this capability with other DMA driver types
is not defined for MCDMA.

Fixes: 6ccd692b

 ("dmaengine: xilinx_dma: Add Xilinx AXI MCDMA Engine driver support")
Signed-off-by: Matthew Murrian <matthew.murrian@goctsi.com>
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Link: https://lore.kernel.org/r/1604473206-32573-4-git-send-email-radhey.shyam.pandey@xilinx.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>