Telephony: Add support for Sprint TW "System select" choices.

Also fixes the no-roaming bug due to the lack of the CDMA_RM_DOMESTIC
option, which forces CDMA_RM_HOME when opening the "Mobile networks"
settings screen.

From CM 10.2: I32129efe217e5f79372aab49e45c668393c3dc2a.

Change-Id: If3de040144e96253ba869cfbcfe8902597ce92b8