Grant vdc access to kmsg

Init is no longer calling vdc with logwrapper, so it must take care of
logging to kmsg directly.

avc: denied { write } for pid=367 comm="vdc" name="kmsg" dev="tmpfs" ino=11056 scontext=u:r:vdc:s0 tcontext=u:object_r:kmsg_device:s0 tclass=chr_file permissive=0

Bug: 36278706
Test: observe vdc logging in kmsg on boot and stderr on normal usage

(cherry picked from commit bc4d3630)

Change-Id: Id7bc2fa87518aa0678c09495267c9e198ca8c968