pinctrl/amd: switch to using a bool for level

The earlier patch can be simplified by using a bool
to indicate level trigger.

Reviewed-by: Pankaj Sen <Pankaj.Sen@amd.com>
Signed-off-by: Nitesh Kumar Agrawal <Nitesh-kumar.Agrawal@amd.com>
[Fixup to earlier manually applied patch]
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>