MSIM: Do not initiate flex map if RAF/modemUuid are invalid

Sometimes due to phone object switch existing phone RAF values
disposed and at same time if flex map initiated, ProxyController
proceeding with flex map using invalid RAF/modemUuid.

To avoid such situation skip initiating flex map if RAF/modemUuid
values are not valid.

- Correct flex map system proeprty name.

Change-Id: I5e836b7c8d841265085c54059d5b989d79c18eaf