sepolicy: remove block_device access from install_recovery

The recovery partition has been assigned a recovery_block_device
type for the AOSP devices, so install_recovery should not need
rw access to the generic block_device type.  Remove it.

Change-Id: I31621a8157998102859a6e9eb76d405caf6d5f0d
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>