pinctrl: aspeed: Format pinconf debug consistent with pinmux

When displaying which pinconf register and field is being touched,
format the field mask so that it's consistent with the way the pinmux
portion formats the mask.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20200910025631.2996342-2-andrew@aj.id.au


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