Mms: CT requirement: Keep CTWAP network specific period after sending/receiving MMS

After sending/downloading MMS, it will release network immediately normally. To meet CT requirement,
Delay specific time to release network. Default time is 100S. Optional value is 100S/80S/60S.

CRs-Fixed: 2391101

Change-Id: I77111f547f6d3b67a5029d83972b3f136c423c9f