pinctrl: ralink: rt2880: preserve error codes

pinctrl: ralink: rt2880: preserve error codes

Some paths in probe function are returning '-EINVAL'
instead of preserve original code from called functions.
Change them to preserve all of them.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20201213161721.6514-7-sergio.paracuellos@gmail.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>