Exclude /mnt/vendor from vold's ownership.

Addresses this selinux denial:
avc: denied { search } for name="vendor" dev="tmpfs" ino=11069
scontext=u:r:vold:s0 tcontext=u:object_r:mnt_vendor_file:s0 tclass=dir
permissive=0

Bug: 64905218
Test: fixes above denial.
Change-Id: I670b2148e65c7e0fcabd1e11f5bace0c4f4e18bd
1 file changed