iio: mma9551: fix sparse warning

sparse warnings: (new ones prefixed by >>)

>> drivers/iio/accel/mma9551.c:554:57: sparse: mixing different enum types
   drivers/iio/accel/mma9551.c:554:57:     int enum mma9551_tilt_axis  versus
   drivers/iio/accel/mma9551.c:554:57:     int enum mma9551_gpio_pin
>> drivers/iio/accel/mma9551.c:576:57: sparse: mixing different enum types
   drivers/iio/accel/mma9551.c:576:57:     int enum mma9551_tilt_axis  versus
   drivers/iio/accel/mma9551.c:576:57:     int enum mma9551_gpio_pin

Signed-off-by: Vlad Dogaru <vlad.dogaru@intel.com>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Reviewed-by: Irina Tirdea <irina.tirdea@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/accel/mma9551.c

@@ -551,7 +551,8 @@ static int mma9551_config_incli_event(struct iio_dev *indio_dev,
 		return 0;
 
 	if (state == 0) {
-		ret = mma9551_gpio_config(data->client, mma_axis,
+		ret = mma9551_gpio_config(data->client,
+					  (enum mma9551_gpio_pin)mma_axis,
 					  MMA9551_APPID_NONE, 0, 0);
 		if (ret < 0)
 			return ret;
@@ -573,7 +574,8 @@ static int mma9551_config_incli_event(struct iio_dev *indio_dev,
 			return -EINVAL;
 		}
 
-		ret = mma9551_gpio_config(data->client, mma_axis,
+		ret = mma9551_gpio_config(data->client,
+					  (enum mma9551_gpio_pin)mma_axis,
 					  MMA9551_APPID_TILT, bitnum, 0);
 		if (ret < 0)
 			return ret;