Telephony: Add support for NETWORK_TYPE_GSM

Add support for NETWORK_TYPE_GSM in TelephonyManager and
corresponding mapping in ServicState.java so that when
application queries getVoiceNetworkType() and currently
camped rat is GSM, they get network mode as GSM instead
of network mode unknown.

Change-Id: I5e971c625532696776b9555ad8cfd85eba4fc423
CRs-Fixed: 526435
(cherry picked from commit 3e01fcec13725955f0ca3fb20730ff21f4edc128)
(cherry picked from commit c70f5687965908cd585e52901cf6cd88bd405140)
(cherry picked from commit 8e3c2300729ecb3cd3e6b640b0174f49e2189f0c)
Telephony: Add TD-SCDMA network modes

1)TD-SCDMA Signal Strength support.
2)Add TD-SCDMA network type support in MobileDataStateTracker class
to identify TD-SCDMA as UMTS variant and use the relevant
kernel data stack tcp buffer sizes defined.
3) Add TD-SCDMA to the list of supported network modes.

Change-Id: I158821574484bfaf47d1660406e591e2afb3be5e
CRs-Fixed: 403258, 479310
(cherry picked from commit 2ba1b7292c6b458fb72587c1f29a5c00b70717cd)
(cherry picked from commit d58b065e7e3d84461a3c981e7a7d4673f3567ef5)
(cherry picked from commit 7844d69d3d323b3969766309c2ad5bc80411fbae)
SignalStrength: Hotfix TD-SCDMA

These checks need to be reviewed, they're making unwarranted assumptions
about signal value formats and possible tech combos.
This appears to work for all possible scenarios I was able to test,
but the "LTE checks" shouln't be necessary at all.

Change-Id: I889e17e79ca2b1b5fcaa393741e19bef9d3f4229
SignalStrength: Hotfix TD-SCDMA take 2

The previous approach worked for 3G, but failed with TD-LTE. Let's
try something different to make them both work, and use the derpy
LTE checks only if a GSM signal is present.

Change-Id: I77e3b5a1e0f99df30c32b102918af418a20077c1