Add Documentation to help users use endpoint library to enable endpoint
mode in the PCI controller and add new PCI endpoint functions.
Signed-off-by: NKishon Vijay Abraham I <kishon@ti.com>
Acked-By: NJoao Pinto <jpinto@synopsys.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>