USB: ohci-at91: fix vbus_pin_active_low handling

The information is not properly taken into account
for {get|set}_power() functions.

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>
Cc: stable <stable@vger.kernel.org>		[3.2+]