codecs: register SBC codec once.

codecs: register SBC codec once.

Somehow the registration of the SBC codec was duplicated, which does not
(yet) cause an error message, but also doesn't work.
Remove the duplicate registration.

Change-Id: Ic22ba66fd65b326fb2688300dad8f9b81081c7e5
Signed-off-by: Jaap Keuter <jaap.keuter@xs4all.nl>
Reviewed-on: https://code.wireshark.org/review/25506
Reviewed-by: Alexis La Goutte <alexis.lagoutte@gmail.com>
Petri-Dish: Alexis La Goutte <alexis.lagoutte@gmail.com>
Tested-by: Petri Dish Buildbot
Reviewed-by: Michael Mann <mmann78@netscape.net>