iio: magnetometer: ak8975: Fix typo, uniform measurement unit style

Minor comment style edits.
Signed-off-by: Jonathan Albrieux <jonathan.albrieux@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/magnetometer/ak8975.c

@@ -385,9 +385,9 @@ static int ak8975_power_on(const struct ak8975_data *data)
 		return ret;
 	}
 	/*
-	 * According to the datasheet the power supply rise time i 200us
+	 * According to the datasheet the power supply rise time is 200us
 	 * and the minimum wait time before mode setting is 100us, in
-	 * total 300 us. Add some margin and say minimum 500us here.
+	 * total 300us. Add some margin and say minimum 500us here.
 	 */
 	usleep_range(500, 1000);
 	return 0;