hw/arm: ast2400/ast2500: Wire up EHCI controllers

hw/arm: ast2400/ast2500: Wire up EHCI controllers

Initialize EHCI controllers on AST2400 and AST2500 using the existing
TYPE_PLATFORM_EHCI. After this change, booting ast2500-evb into Linux
successfully instantiates a USB interface.

ehci-platform 1e6a3000.usb: EHCI Host Controller
ehci-platform 1e6a3000.usb: new USB bus registered, assigned bus number 1
ehci-platform 1e6a3000.usb: irq 21, io mem 0x1e6a3000
ehci-platform 1e6a3000.usb: USB 2.0 started, EHCI 1.00
usb usb1: New USB device found, idVendor=1d6b, idProduct=0002, bcdDevice= 5.05
usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
usb usb1: Product: EHCI Host Controller

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20200206183437.3979-1-linux@roeck-us.net
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>