iio: light: cm32181: Fix formatting and docrot issues in cm32181_acpi_get_cpm()

Fixes the following W=1 kernel build warning(s):

 drivers/iio/light/cm32181.c:107: warning: Function parameter or member 'dev' not described in 'cm32181_acpi_get_cpm'
 drivers/iio/light/cm32181.c:107: warning: Function parameter or member 'obj_name' not described in 'cm32181_acpi_get_cpm'
 drivers/iio/light/cm32181.c:107: warning: Function parameter or member 'values' not described in 'cm32181_acpi_get_cpm'
 drivers/iio/light/cm32181.c:107: warning: Function parameter or member 'count' not described in 'cm32181_acpi_get_cpm'

Cc: Kevin Tsai <ktsai@capellamicro.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>