If userdata is on f2fs and encrypted (stock config for userdata),
/cache/recovery/block.map is not created due to this denial:
05-01 13:43:47.512 6538 6538 W uncrypt : type=1400 audit(0.0:10): avc: denied { sys_admin } for capability=21 scontext=u:r:uncrypt:s0 tcontext=u:r:uncrypt:s0 tclass=capability permissive=0
Without block.map the automatic flashing of the OTA without user
interaction fails, and the user needs to manually mount data, and
flash the OTA manually.
Change-Id: I6ecb84e8b730d4c641a8bd8769043dfbfb817b83
