ARM: at91/USB host: specify and handle properly vbus_pin_active_low

Due to an error while handling vbus_pin_active_low in ohci-at91 driver,
the specification of this property was not good in devices/board files.

Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: stable <stable@vger.kernel.org>         [3.2+]