tools: gpio: Small updates for output format

Use %2d for the GPIO line number. This should align the results
horziontally for most gpio chips.

The GPIO label uses quotes for real values. For GPIO names this is
currently missing. The patch adds the missing quote.

Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>