gpio: siox: Do not call gpiochip_remove() on errorpath

gpiochip_remove() was called on the errorpath if
gpiochip_add() failed: this is wrong, if the chip failed
to add it is not there so it should not be removed.

Fixes: be8c8fac ("gpio: new driver to work with a 8x12 siox")
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>