[ARM] 5566/1: Remove at91_gpiolib_request

Remove at91_gpiolib_request. It returns -EPERM if a request pin is not
in GPIO mode, however we want to be able to gpio_request alternative
function pins to reserve them, and in some cases we need to be able to
use the gpiolib functions on alternative function pins.

Signed-off-by: Ryan Mallon <ryan@bluewatersys.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>