iio: chemical: ccs811: Typo correction in HW_ID_VALUE constant define naming

This particular constant was named with prefix "CCS881", which should be
"CCS811" instead, just like the rest of constant names in the file, as this
driver implementation is for AMS CCS811 sensor. "CCS881" could literally be
referring to another sensor product unrelated to AMS CCS811 sensor.

Signed-off-by: Richard Lai <richard@richardman.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>