restore permissions to /vendor for non-treble devices

Relabeling /vendor and /system/vendor to vendor_file removed
previously granted permissions. Restore these for non-treble devices.

Addresses:
avc: denied { execute_no_trans } for pid=2944 comm="dumpstate"
path="/system/vendor/bin/wpa_cli" dev="mmcblk0p10" ino=1929
scontext=u:r:dumpstate:s0 tcontext=u:object_r:vendor_file:s0
tclass=file

And potentially some other bugs that have yet to surface.

Bug: 37105075
Test: build Fugu
Change-Id: I8e7bd9c33819bf8206f7c110cbce72366afbcef8