Fix tcp buffer sizes on LTE_CA.

Make them the same as LTE since we don't have an overlay setting for
LTE_CA (nor do we want one).

Also noticed that on CDMA/CDMA+LTE we didn't enable the ratcheting
mechanism so we'd bounce between LTE and LTE_CA unnecessarily.

bug:30269506
Change-Id: I34d308c7ee92745ce18700f31b8b68e78728b01e