pinctrl: sunxi: Enforce the strict mode by default

The strict mode should always have been enabled on our driver, and leaving
it unchecked just makes it harder to find a migration path as time passes.

Let's enable it by default now so that hopefully the new SoCs should be
safe.

Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>