mtk: Add new atoms

Add atoms that have already been added to ril plugins: call barring,
radio settings and another GPRS context for MMS.
mtkmodem: Fix double registration to voicecall

mtk modem was registering twice to the voicecall atom: once in
rilmodem voicecall driver and once in mtkmodem voicecall driver.
mtk: Fix devinfo on boot

Serial (IMEI) and Revision modem properties were not shown when
re-starting the phone, as the devinfo atom was created when the radio
state was still unavailable.
Merge pull request #82 from alfonsosanchezbeato/mtk-update

Mtk update
gril: Fix parsing of replies for infineon modem

Adjustments to parsing code are needed to handle some request replies
from infineon modem.
unit: Tests for infineon ril modem

Specific tests for some infineon replies.
plugins: fix android-provision crash

Fix a crash in provision_get_settings() caused by the code
freeing 'error' with g_error_free() but not setting the value
to NULL afterwards.  This can cause a subsequent call to
g_error_free() to happen again with an invalid pointer value.
Merge pull request #81 from alfonsosanchezbeato/infineon

Fix parsing of replies for infineon modem
Merge pull request #84 from tonyespy/fix-provision-crash

Approved.