arm: vt8500: Increase available GPIOs on arch-vt8500

With the inclusion of the pin control driver, more GPIO pins have been
identified on the arch-vt8500 SoCs requiring an increase in the available
GPIOs.

Signed-off-by: Tony Prisk <linux@prisktech.co.nz>
Acked-by: Linus Walleij <linus.walleij@linaro.org>