Allow vendor_init to write to misc_block_device

am: db465285

Change-Id: Icd5639ebae411b2c6e6acaf0db143794351dcb1c

public/domain.te

@@ -600,6 +600,7 @@ neverallow {
   -init
   -uncrypt
   -update_engine
+  -vendor_init
   -vold
   -recovery
   -ueventd

public/vendor_init.te

@@ -146,6 +146,9 @@ allow vendor_init serialno_prop:file { getattr open read };
 # Vendor init can perform operations on trusted and security Extended Attributes
 allow vendor_init self:global_capability_class_set sys_admin;
 
+# Raw writes to misc block device
+allow vendor_init misc_block_device:blk_file w_file_perms;
+
 not_compatible_property(`
     set_prop(vendor_init, {
       property_type