staging: iio: isl29028: only set proximity sampling rate when proximity is enabled

isl29028_chip_init_and_power_on() calls isl29028_set_proxim_sampling()
and this is not needed until the user actually needs to take a proximity
reading. This patch moves the isl29028_set_proxim_sampling() call from
isl29028_chip_init_and_power_on() to isl29028_enable_proximity().
This sets the stage for faster resume times from the runtime power
management if the user is only querying the ALS/IR sensor.
Signed-off-by: Brian Masney <masneyb@onstation.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/staging/iio/light/isl29028.c

@@ -107,6 +107,10 @@ static int isl29028_enable_proximity(struct isl29028_chip *chip)
 {
 	int ret;
 
+	ret = isl29028_set_proxim_sampling(chip, chip->prox_sampling);
+	if (ret < 0)
+		return ret;
+
 	ret = regmap_update_bits(chip->regmap, ISL29028_REG_CONFIGURE,
 				 ISL29028_CONF_PROX_EN_MASK,
 				 ISL29028_CONF_PROX_EN);
@@ -449,10 +453,6 @@ static int isl29028_chip_init_and_power_on(struct isl29028_chip *chip)
 		return ret;
 	}
 
-	ret = isl29028_set_proxim_sampling(chip, chip->prox_sampling);
-	if (ret < 0)
-		return ret;
-
 	return isl29028_set_als_scale(chip, chip->lux_scale);
 }