IQ record/playback bug fixes

This issue relates to usage of IQ record playback. The following problems are solved:

1. IQ record playback is not compatible with phy_test_mode. When eNB is built with --usrp-recplay, it shall be run with phy_test_mode = 0 config parameter.
2. Provide a specific 25 PRB USRP config file (with phy_test_mode = 0) for IQ record/playback usage
3. Fix some issues after last merge (exiting softmodem when --subframes-loops is reached, others)

The all issue will be validated with a single UE scenario