IMS : Add api to support cache retrieval

- isSimlessRttDowgradeSupported is returning the saved
  cache of previous sim to display in e911 rtt downgrade
  option during call.
- simless_rtt_downgrade_supported is a new key added to
  store the cached value of carrier config in the last sim.

Change-Id: I04b6450aa4d7c3c421d33f4e9041d739cd4eaf47
CRs-Fixed: 3090631
2 files changed
tree: 80821c9bb4d12b6a387ac1c2cc7d4c22967f7c4e
  1. extphone/
  2. ims/
  3. internal/
  4. qti-hidl-wrapper/
  5. qti-utils/