pinctrl: sunxi: use gpiolib API to mark a GPIO used as an IRQ

When an IRQ is started on a GPIO line, mark this GPIO as IRQ in
the gpiolib so we can keep track of the usage centrally.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
pinctrl: sunxi: number gpio ranges starting from 0

The pinctrl-sunxi driver originally used the pin number as the gpio
range offset. This resulted in large, bogus gpio numbers for the
new sun6i-a31-r pinctrl devices.

This patch makes the driver number the gpios ranges starting from an
offset of 0, by subtracting the pin_base number from the pin number.
This also makes the system-wide gpio number match the pin number.

Tested on sun8i with sysfs exported gpios.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>