pinctrl: mediatek: fix global-out-of-bounds issue

When eint virtual eint number is greater than gpio number,
it maybe produce 'desc[eint_n]' size globle-out-of-bounds issue.

Signed-off-by: Guodong Liu <guodong.liu@mediatek.corp-partner.google.com>
Signed-off-by: Zhiyong Tao <zhiyong.tao@mediatek.com>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Link: https://lore.kernel.org/r/20211110071900.4490-2-zhiyong.tao@mediatek.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>