gpio: davinci: Stop using ARCH_NR_GPIOS

Since commit 14e85c0e

 ("gpio: remove gpio_descs global array")
there is no global limitation anymore on the number of GPIOs in
the system so don't clamp the number of GPIOs with ARCH_NR_GPIOS.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>