USB: ohci-at91 uses generic GPIO calls

Update the ohci-at91 bus glue to start understanding about the per-port
power switch GPIOs it's given (on the sam9263-ek and potentially other
boards).  For the moment this just claims them and forces them active
(assuming active-low power enables) whenever the HCD is loaded.

The assumption is still that board setup configures the GPIOs.  Using
gpio_request() tracks actual usage and guards against conflict.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>