Add endpoint mode support to designware driver. This uses the EP Core layer
introduced recently to add endpoint mode support.  *Any* function driver
can now use this designware device in order to achieve the EP
functionality.
Signed-off-by: NKishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>