phy: usb: phy-brcm-usb: Add Broadcom STB USB phy driver

Add a new USB Phy driver for Broadcom STB SoCs. This driver
supports Broadcom STB ARM SoCs. This driver in
combination with the Broadcom STB ohci, ehci and xhci
drivers will enable USB1.1, USB2.0 and USB3.0 support.
This Phy driver also supports the Broadcom BDC gadget
driver.

Signed-off-by: Al Cooper <alcooperx@gmail.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>