rilmodem: Consider special parameters for MTK

MTK modems need for the SETUP_DATA_CALL request the call ID and a
special data profile in the case of MMS to be able to create contexts.
gril: Use specific MTK params for data call setup
ril: Set the type for GPRS contexts
mtk: Set the type for GPRS contexts
Merge pull request #106 from alfonsosanchezbeato/mtk-mms-ctx

MTK modem MMS fix