USB: ohci-at91: rework and fix initialization

The DT information are filled in a pdata structure and then passed on
to the usual check code of the probe function. Thus we do not need to
redo the gpio checking and irq configuration in the DT-related code.
On the other hand, we setup GPIO direction in driver for vbus and
overcurrent. It will be useful when moving to pinctrl subsystem.

Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>