gsmtap: Add GSMTAP_GPRS_CS() / GSMTAP_GPRS_MCS()

As requested by Mike Morrin <Mike.Morrin@ipaccess.com>, we introduce
GSMTAP sub-types for all the different GPRS and EGPRS coding schemes.

This is neccessary due to the fact that the RLC PDU doesn't contain any
explicit indication of the coding scheme used on the radio layer.
1 file changed