pinctrl: max77620: add OF dependency

Drivers using pinconf_generic_params tables cannot be built with
CONFIG_OF disabled:

drivers/pinctrl/pinctrl-max77620.c:53:44: error: array type has incomplete element type ‘struct pinconf_generic_params’
drivers/pinctrl/pinctrl-max77620.c:55:3: error: field name not in record or union initializer
drivers/pinctrl/pinctrl-max77620.c:55:3: note: (near initialization for ‘max77620_cfg_params’)
drivers/pinctrl/pinctrl-max77620.c:56:3: error: field name not in record or union initializer

This adds a dependency for max77620 to disallow that configuration.

Alternatively, we could rework the pinctrl infrastructure to make the
configuration valid for compile-testing.

Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Lee Jones <lee.jones@linaro.org>
Fixes: 453943dc8f45 ("mfd: Enable compile testing for max77620 and max77686")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>