gpio: aspeed: Add support for reset tolerance

Use the new pinconf parameter for state persistence to expose the
associated capability of the Aspeed GPIO controller.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>