hwmon: (pmbus/isl68137) Fix unchecked return value and use sysfs_emit()

commit 86259558e422b250aa6aa57163a6d759074573f5 upstream.

isl68137_avs_enable_show_page() uses the return value of
pmbus_read_byte_data() without checking for errors. If the I2C transaction
fails, a negative error code is passed through bitwise operations,
producing incorrect output.

Add an error check to propagate the return value if it is negative.
Additionally, modernize the callback by replacing sprintf()
with sysfs_emit().

Fixes: 038a9c3 ("hwmon: (pmbus/isl68137) Add driver for Intersil ISL68137 PWM Controller")
Cc: stable@vger.kernel.org
Signed-off-by: Sanman Pradhan <psanman@juniper.net>
Link: https://lore.kernel.org/r/20260318193952.47908-2-sanman.pradhan@hpe.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Sanman Pradhan

drivers/hwmon/pmbus/isl68137.c

@@ -96,8 +96,11 @@ static ssize_t isl68137_avs_enable_show_page(struct i2c_client *client,
 {
 	int val = pmbus_read_byte_data(client, page, PMBUS_OPERATION);
 
-	return sprintf(buf, "%d\n",
-		       (val & ISL68137_VOUT_AVS) == ISL68137_VOUT_AVS ? 1 : 0);
+	if (val < 0)
+		return val;
+
+	return sysfs_emit(buf, "%d\n",
+			   (val & ISL68137_VOUT_AVS) == ISL68137_VOUT_AVS);
 }
 
 static ssize_t isl68137_avs_enable_store_page(struct i2c_client *client,