sepolicy: msm8937: changes required to support dynamic partition

1) Label super partition as 'super_block_device'
2) Allow recovery to read sysfs_dm entries.
3) Add appropriate labels for vbmeta_system_[ab] and recovery_[ab]
   block devices and allow hal_bootctl to access them.

Change-Id: Ic1e08e64cf6dd12823dc14c5c857703c76721388