linux-phytec-ti

gpio: max732x: Fix error handling in probe()

This fixes error handling in the function max732x_probe by checking
if the calls to the function max732x_readb fail by returning a error
code.

Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>