gpio: max732x: remove redundant check

The pdata is already checked for its validity. Remove
this redundant check.

Signed-off-by: Gaurav Singh <gaurav1086@gmail.com>
Link: https://lore.kernel.org/r/20200610113630.11922-1-gaurav1086@gmail.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>