sepolicy : addressing denails for cameraserver and hal_camera

Issue: cameraserver crashing while accesing cameraheapmemory
      in CAM1 HAL1 after enforcing treble rules.
Solution: Added hal_allocator allow to cameraserver to get access to
/dev/ashmem.

addressing following denials :
 avc: denied { use } for pid=5088 comm="CAM_strmDatProc" path="/dev/ashmem"
      dev="tmpfs" ino=19159 scontext=u:r:cameraserver:s0
      tcontext=u:r:hal_allocator_default:s0 tclass=fd

  avc:  denied  { find } for interface=android.hardware.graphics.mapper::IMapper pid=815
        scontext=u:r:hal_camera_default:s0 tcontext=u:object_r:hal_graphics_mapper_hwservice:s0
        tclass=hwservice_manager

Change-Id: I18830ae0d12c17e299e4f97979c12487a027faa2