add ueventd to shutdown critial process

- In some devices, some drivers still try to load firmware while shutting
  down, and crashes the kernel. So keep ueventd to prevent such case.

bug: 38203024
Test: reboots

(cherry picked from commit 7264bee9)

Change-Id: Ifc725f906de01eba552c782b8ec0d7bd11d089d0
(cherry picked from commit 9c91d902)