Reboot the soundtrigger HAL on failure

... and avoid rebooting system_server.
There is no benefit in rebooting the system_server.

Fixes: 153461865
Test: Tested via a shell command that the sound trigger middleware
      service can indeed reboot the HAL and correctly recover from it
      dying.
Change-Id: Ie476968b6acf97bf701d0e2929e7bd099e19cd56