Allow vendor_init to set vendor_build_type_prop

[   18.240834] selinux: avc:  denied  { set } for  scontext=u:r:vendor_init:s0 tcontext=u:object_r:vendor_build_type_prop:s0 tclass=property_service permissive=0\x0a
[   18.258715] init: Do not have permissions to set 'ro.vendor.build.type' to 'userdebug' in property file '/vendor/build.prop': SELinux permission check failed

Bug: 143504506
Test: flash selinux modules to device and find avc errors gone
Change-Id: Ie19418fa0dd9c80d054e197850013a880bca6593