ARM/USB: at91/ohci-at91: rename vbus_pin_inverted to vbus_pin_active_low

Allows to configure independently the vbus_pin associated with each port.
Matches usual naming scheme.

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Cc: linux-usb@vger.kernel.org