Add pair event device class and fix timestamp

Added a function to get the device class to use with pair events.
Also update check_cod_hid as it was only being used with COD_HID_MAJOR.
Also fixed an issue with pair event timestamps where they were
using the wrong clock.

Bug: 27499938
Change-Id: I0805d7a3f82b28e7d7e73d80818948843f51a82b