Allow setopt on bluetooth's unix_stream_socket.

This is extremely useful as it allows timeouts on the socket.
Since ioctl is allowed, setopt shouldn't be a problem.

Resolves denials, in 3rd party apps, such as:

avc:  denied  { setopt } for  pid=18107 comm="AudioRouter-6"
scontext=u:r:untrusted_app:s0 tcontext=u:r:bluetooth:s0
tclass=unix_stream_socket

Change-Id: I6f38d7b86983c517575b735f43b62a2ed811e81c
Signed-off-by: Sérgio Faria <sergio91pt@gmail.com>