dmaengine: imx-sdma: Remove platform data support

Since 5.10-rc1, i.MX has been converted to a devicetree-only platform.

The platform data support in this driver was only used for non-DT
platforms.

Remove the platform data support as it has no more users.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Link: https://lore.kernel.org/r/20210118121549.1625217-1-festevam@gmail.com


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