gpio: Don't override the error code in probe error handling

Otherwise, we return 0 in probe error paths when gpiochip_remove() returns 0.
Also show error message if gpiochip_remove() fails.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Cc: Tomoya MORINAGA <tomoya.rohm@gmail.com>
Cc: Denis Turischev <denis@compulab.co.il>
Cc: Lars Poeschel <poeschel@lemonage.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>