pinctrl: mediatek: common: Fix probe failure for devices without EINT

pinctrl: mediatek: common: Fix probe failure for devices without EINT

Some pinctrl devices like mt6397 or mt6392 don't support EINT at all, but
the mtk_eint_init function is always called and returns -ENODEV, which
then bubbles up and causes probe failure.

To address this only call mtk_eint_init if EINT pins are present.

Tested on Xiaomi Mi Smart Clock x04g (mt6392).

Fixes: e46df235b4e6 ("pinctrl: mediatek: refactor EINT related code for all MediaTek pinctrl can fit")
Signed-off-by: Luca Leonardo Scorcia <l.scorcia@gmail.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Linus Walleij <linusw@kernel.org>