For proper USB function the usbmisc registers have to be initialized.
This patch adds a driver which matches for the usbmisc registers. This
driver is called from a new driver which binds to the USB ports to
configure the misc registers. After that the driver registers the EHCI
driver and an ULPI transceiver if necessary. Currently only host mode
is supported, but device support can be added later.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>