PCI: dwc: dra7xx: Workaround for errata id i870

According to errata i870, access to the PCIe slave port that are not 32-bit
aligned will result in incorrect mapping to TLP Address and Byte enable
fields.

Accessing non 32-bit aligned data causes incorrect data in the target
buffer if memcpy is used. Implement the workaround for this errata here.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>