[PATCH] iio: adc: ti-ads7950: Fix build error without CONFIG_GPIOLIB

[Yue Haibing]

From: YueHaibing <yuehaibing@xxxxxxxxxx>

When building with CONFIG_GPIOLIB is not set
gcc warns this:

drivers/iio/adc/ti-ads7950.c:75:19: error: field chip has incomplete type
  struct gpio_chip chip;
                   ^~~~
drivers/iio/adc/ti-ads7950.c: In function ti_ads7950_set:
drivers/iio/adc/ti-ads7950.c:409:32: error: implicit declaration of function gpiochip_get_data; did you mean acpi_get_data? [-Werror=implicit-function-declaration]
  struct ti_ads7950_state *st = gpiochip_get_data(chip);
                                ^~~~~~~~~~~~~~~~~
                                acpi_get_data

Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
Fixes: c97dce792dc8 ("iio: adc: ti-ads7950: add GPIO support")
Signed-off-by: YueHaibing <yuehaibing@xxxxxxxxxx>
---
 drivers/iio/adc/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 846c7ac..f760269 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -968,7 +968,7 @@ config TI_ADS1015
 
 config TI_ADS7950
 	tristate "Texas Instruments ADS7950 ADC driver"
-	depends on SPI
+	depends on SPI && GPIOLIB
 	select IIO_BUFFER
 	select IIO_TRIGGERED_BUFFER
 	help
-- 
2.7.4