libpayload: Add init() function to hci_t and rework uhci_reset()

uhci_reset() differs in semantics compared to the other HCI's reset()
implementations. uhci_reset() does some initialization work after a
controller reset. So move the initialization part to a new function,
uhci_reinit(), which get's exported through a new entry in hci_t:
hci_t.init().

Warning: This breaks code that relies on the current, special,
counterintuitive behaviour of uhci_reset(). If one wants a working host
controller after calling hci_t.reset(), he should call hci_t.init()
afterwards.

Change-Id: Ia7ce80865d12d11157645ce251f77f349f8e3c34
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: http://review.coreboot.org/1851
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

payloads/libpayload/include/usb/usb.h

@@ -127,6 +127,9 @@ struct usbdev_hc {
 	/* reset():     Perform a controller reset. The controller needs to
 	                be (re)initialized afterwards to work (again). */
 	void (*reset) (hci_t *controller);
+	/* init():      Initialize a (previously reset) controller
+	                to a working state. */
+	void (*init) (hci_t *controller);
 	/* shutdown():  Stop operation, detach host controller and shutdown
 	                this driver instance. After calling shutdown() any
 			other usage of this hci_t* is invalid. */