thermal: qcom: Fix comparison with uninitialized variable channels_available

Currently the check of chip->channels[i].channel is against an the
uninitialized variable channels_available.  I believe the variable
channels_available needs to be fetched first by the call to adc_tm5_read
before the channels check. Fix the issue swapping the order of the
channels check loop with the call to adc_tm5_read.

Addresses-Coverity: ("Uninitialized scalar variable")
Fixes: ca66dca ("thermal: qcom: add support for adc-tm5 PMIC thermal monitor")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210216151626.162996-1-colin.king@canonical.com

Author: Colin Ian King

drivers/thermal/qcom/qcom-spmi-adc-tm5.c

@@ -375,20 +375,20 @@ static int adc_tm5_init(struct adc_tm5_chip *chip)
 	int ret;
 	unsigned int i;
 
-	for (i = 0; i < chip->nchannels; i++) {
-		if (chip->channels[i].channel >= channels_available) {
-			dev_err(chip->dev, "Invalid channel %d\n", chip->channels[i].channel);
-			return -EINVAL;
-		}
-	}
-
 	ret = adc_tm5_read(chip, ADC_TM5_NUM_BTM,
 			   &channels_available, sizeof(channels_available));
 	if (ret) {
 		dev_err(chip->dev, "read failed for BTM channels\n");
 		return ret;
 	}
 
+	for (i = 0; i < chip->nchannels; i++) {
+		if (chip->channels[i].channel >= channels_available) {
+			dev_err(chip->dev, "Invalid channel %d\n", chip->channels[i].channel);
+			return -EINVAL;
+		}
+	}
+
 	buf[0] = chip->decimation;
 	buf[1] = chip->avg_samples | ADC_TM5_FAST_AVG_EN;
 	buf[2] = ADC_TM5_TIMER1;