sdm710: Label persist block device

Resolves:
W e2fsck  : type=1400 audit(0.0:16): avc: denied { read write } for name="sdf7" dev="tmpfs" ino=11779 scontext=u:r:fsck:s0 tcontext=u:object_r:block_device:s0 tclass=blk_file permissive=0

Change-Id: I653a088d84479a2e096e0d2bece770c1430b694f