iio: magnetometer: ak8975: fix wrong errno on return

The driver currently returns -EINVAL on polling timeout instead of
-ETIMEDOUT.

Replace return code for -ETIMEDOUT and remove unnecessary error
message as -ETIMEDOUT is a standard POSIX error. Also replace
instances of -EINVAL in comments.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Joshua Crofts <joshua.crofts1@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Author: cjd8

drivers/iio/magnetometer/ak8975.c

@@ -662,10 +662,8 @@ static int wait_conversion_complete_gpio(struct ak8975_data *data)
 			break;
 		timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
 	}
-	if (!timeout_ms) {
-		dev_err(&client->dev, "Conversion timeout happened\n");
-		return -EINVAL;
-	}
+	if (!timeout_ms)
+		return -ETIMEDOUT;
 
 	ret = i2c_smbus_read_byte_data(client, data->def->ctrl_regs[ST1]);
 	if (ret < 0)
@@ -695,15 +693,13 @@ static int wait_conversion_complete_polled(struct ak8975_data *data)
 			break;
 		timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
 	}
-	if (!timeout_ms) {
-		dev_err(&client->dev, "Conversion timeout happened\n");
-		return -EINVAL;
-	}
+	if (!timeout_ms)
+		return -ETIMEDOUT;
 
 	return read_status;
 }
 
-/* Returns 0 if the end of conversion interrupt occurred or -ETIME otherwise */
+/* Returns 0 if the end of conversion interrupt occurred or -ETIMEDOUT otherwise */
 static int wait_conversion_complete_interrupt(struct ak8975_data *data)
 {
 	int ret;
@@ -713,7 +709,7 @@ static int wait_conversion_complete_interrupt(struct ak8975_data *data)
 				 AK8975_DATA_READY_TIMEOUT);
 	clear_bit(0, &data->flags);
 
-	return ret > 0 ? 0 : -ETIME;
+	return ret > 0 ? 0 : -ETIMEDOUT;
 }
 
 static int ak8975_start_read_axis(struct ak8975_data *data,