Transceiver52: allow for handling of TCH/H slots

Although currently unsupported in GSM core, enable TCH/H
support in Transceiver52M for testing and future availability.

Signed-off-by: Thomas Tsou <tom@tsou.cc>

git-svn-id: http://wush.net/svn/range/software/public/openbts/trunk@5169 19bc5d8c-e614-43d4-8b26-e1612bc8e597