gpio: Get rid of duplicate of_node assignment in the drivers

GPIO library does copy the of_node from the parent device of
the GPIO chip, there is no need to repeat this in the individual
drivers. Remove these assignment all at once.

For the details one may look into the of_gpio_dev_init() implementation.

While at it, remove duplicate parent device assignment where it is the case.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-By: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>