regulator: da9121: include linux/gpio/consumer.h

regulator: da9121: include linux/gpio/consumer.h

When CONFIG_GPIOLIB is disabled, the declarations from linux/gpio/consumer.h
are not visible:

drivers/regulator/da9121-regulator.c:371:14: error: implicit declaration of function 'fwnode_gpiod_get_index' [-Werror,-Wimplicit-function-declaration]
        ena_gpiod = fwnode_gpiod_get_index(of_fwnode_handle(np), "enable", 0,
                    ^
drivers/regulator/da9121-regulator.c:372:7: error: use of undeclared identifier 'GPIOD_OUT_HIGH'
                                                GPIOD_OUT_HIGH |
                                                ^
drivers/regulator/da9121-regulator.c:373:7: error: use of undeclared identifier 'GPIOD_FLAGS_BIT_NONEXCLUSIVE'
                                                GPIOD_FLAGS_BIT_NONEXCLUSIVE,

Include this explicitly to help compile testing.

Fixes: 46c413d5bb23 ("regulator: da9121: Add support for device variants via devicetree")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20201204165229.3754763-1-arnd@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>