gpio: max730x: eliminate double free

The function __max730x_remove is called from the remove functions of
drivers/gpio/gpio-max7300.c and drivers/gpio/gpio-max7301.c.  In both
cases, the probe function allocates ts using devm_kzalloc.  Explicitly
freeing such a value with kfree will cause a double free.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>