iio: tsl2772: fix all kernel-doc warnings

iio: tsl2772: fix all kernel-doc warnings

Use the correct kernel-doc notation for struct members to eliminate
kernel-doc warnings:

Warning: include/linux/platform_data/tsl2772.h:88 struct member
 'prox_diode' not described in 'tsl2772_settings'
Warning: include/linux/platform_data/tsl2772.h:88 struct member
 'prox_power' not described in 'tsl2772_settings'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>