[PATCH 1/5] pinctrl: allows not to define the get_group_pins operation

When using a group only pinctrl driver, which does not have any information on the pins it is useless to define a get_group_pins always returning an empty list of pins. When not using get_group_pin[1], a driver must implement it so pins = NULL and num_pins = 0. This patch makes it the default

[PATCH 1/5] pinctrl: allows not to define the get_group_pins operation

When using a group only pinctrl driver, which does not have any information on the pins it is useless to define a get_group_pins always returning an empty list of pins. When not using get_group_pin[1], a driver must implement it so pins = NULL and num_pins = 0. This patch makes it the default