dmaengine: ptdma: Add debugfs entries for PTDMA

Expose data about the configuration and operation of the
PTDMA through debugfs entries: device name, capabilities,
configuration, statistics.

Signed-off-by: Sanjay R Mehta <sanju.mehta@amd.com>
Link: https://lore.kernel.org/r/1629208559-51964-4-git-send-email-Sanju.Mehta@amd.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>