rild: grant priv ioctl commands for udp sockets

Fixes wifi tethering.

avc: denied { ioctl } for pid=657 comm="rild" path="socket:[40758]" dev="sockfs" ino=40758 ioctlcmd=89fd scontext=u:r:rild:s0 tcontext=u:r:rild:s0 tclass=udp_socket permissive=0

Change-Id: Iace07595eb2159500050ca1a1092f59f879c011d