tizenaudio-policy: Apply volume type to output stream of module-loopback

tizenaudio-policy: Apply volume type to output stream of module-loopback

Output stream of module-loopback has not been applied volume type.
It is fixed and now it is possible to control the volume of the
output stream in case of loopback feature if a volume type is defined
to the loopback role in stream-map.json.

Here's an example to use media volume type.(in stream-map.json)
  {
    "role":"loopback",
    "priority" : 2,
    "route-type" : "manual",
    "volume-types":{"in":"none","out":"media"},
    "avail-in-devices":["builtin-mic","usb-audio"],
    "avail-out-devices":["builtin-speaker","usb-audio","bt-a2dp"],
    "avail-frameworks":["sound-manager"]
  },

Change-Id: I8335f84817ff6a3d7282c283c150c96baccf6f99
Signed-off-by: Sangchul Lee <sc11.lee@samsung.com>