Allow dhcp rawip_socket permissions.

dhcpcd opens a raw ip socket in ipv6rs_open() to use ICMPv6.  This
facility should be available for all devices which have a need to
use it.

Addresses the following denials:
<5>[   42.699877] type=1400 audit(1392332560.306:8): avc:  denied  { create } for  pid=983 comm="dhcpcd" scontext=u:r:dhcp:s0 tcontext=u:r:dhcp:s0 tclass=rawip_socket
<5>[   42.699993] type=1400 audit(1392332560.306:9): avc:  denied  { setopt } for  pid=983 comm="dhcpcd" lport=58 scontext=u:r:dhcp:s0 tcontext=u:r:dhcp:s0 tclass=rawip_socket
<5>[   42.732208] type=1400 audit(1392332560.338:10): avc:  denied  { write } for  pid=983 comm="dhcpcd" lport=58 scontext=u:r:dhcp:s0 tcontext=u:r:dhcp:s0 tclass=rawip_socket

Bug: 12473306
Change-Id: Iee57a0cb4c2d2085a24d4b5fb23a5488f0fd3e03