pinctrl: mt7622: stop using the deprecated pinctrl_add_gpio_range

pinctrl: mt7622: stop using the deprecated pinctrl_add_gpio_range

If the pinctrl node has the gpio-ranges property, the range will be added
by the gpio core and doesn't need to be added by the pinctrl driver.

But for keeping backward compatibility, an explicit pinctrl_add_gpio_range
is still needed to be called when there is a missing gpio-ranges in pinctrl
node in old dts files.

Cc: stable@vger.kernel.org
Fixes: d6ed93551320 ("pinctrl: mediatek: add pinctrl driver for MT7622 SoC")
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>