dmaengine: dw-edma: Add PCIe VSEC data retrieval support

The latest eDMA IP development implements a Vendor-Specific Extended
Capability that contains the eDMA BAR, offset, map format, and the
number of read/write channels available.

Signed-off-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
Link: https://lore.kernel.org/r/0b880b8893ff457ffc1b5071a1c7f47e61ceea1c.1613674948.git.gustavo.pimentel@synopsys.com


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