sepolicy: allow platform to vendor tcmd

fixes denials of
W TcmReceiver: type=1400 audit(0.0:730): avc: denied { connectto }
for path="/dev/socket/tcmd" scontext=u:r: platform_app:s0:c512,c768
tcontext=u:r:vendor_tcmd:s0 tclass=unix_stream_socket permissive=0
app=com.qualcomm.qti.qccvendortest

Change-Id: Ic8ae27b555758f9694981de82716e67b5e4d6c8b