The 7216 has the new USB XHCI controller from Synopsys. While
this new controller and the PHY are similar to the STB versions,
the major differences are:

- Many of the registers and fields in the CTRL block have been
  removed or changed.
- A new set of Synopsys control registers, BCHP_USB_XHCI_GBL, were
  added.
- MDIO functionality has been replaced with direct access registers
  in the BCHP_USB_XHCI_GBL block.
- Power up PHY defaults that had to be changed by MDIO in previous
  chips will now power up with the correct defaults.

A new init module was created for this new Synopsys USB controller.
A new compatible string was added and the driver will dispatch
into one of two init modules based on it. A "reg-names" field was
added so the driver can more easily get optional registers.
A DT bindings document was also added for this driver.
Signed-off-by: Al Cooper <alcooperx@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>