usb: add ehci host driver

Copied directly from linux-linaro-2.6.38, largely commit bb9ebb9a5:

    ENGR00141217-4 USB: Add USB Host/device/otg drivers support

Signed-off-by: Zhang Yan <b34916@freescale.com>
Signed-off-by: Eric Miao <eric.miao@linaro.org>
5 files changed