Fix: Change T200 of LAPDm if SAPI 0 and SAPI 3 share bandwidth on SDCCH

Fix: Change T200 of LAPDm if SAPI 0 and SAPI 3 share bandwidth on SDCCH

We use 1 second on FACCH and 2 seconds on SACCH when SMS is transfered
during a call on TCH. There is no impact on bandwidth, because SAPIs use
differen channels.

In order to correctly transfer SMS during SDCCH, the T200 must be raised
from 1 (SAPI 0) to 2 (SAPI 0 and 3), so T200 will not timeout before
receiving acknowledge from BTS. This is because both SAPIs share the same
ressource on SDCCH. After release of SAPI 3, T200 is lowered back to 1.