dmaengine: xilinx_dma: use devm_platform_ioremap_resource()

Replace the chain of platform_get_resource() and devm_ioremap_resource()
with devm_platform_ioremap_resource(). It simplifies the flow and there
is no functional change.

Fixes below cocinelle warning-
WARNING: Use devm_platform_ioremap_resource for xdev -> regs

Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Link: https://lore.kernel.org/r/1569495060-18117-4-git-send-email-radhey.shyam.pandey@xilinx.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>