Changing ueventd access from vendor_file to vendor_file_type.

This handles any relabeling of vendor_file to a more specific type in
the case of device bringups or future changes to private/file_context
since ueventd will still need read access to all vendor_file's.

Test: Ueventd has read access to any vendor_file_type
Change-Id: I922af54c76d1ef46ea6536e6dc945b37bcc2126a