Fix issue with Telecom CTS tests.

A Telecom CTS test adopts shell permission and registers a phone state
listener which listens for emergency calls.  The telecom CTS tests
adopt shell identity to get READ_ACTIVE_EMERGENCY_SESSION.  However,
it was neglected to add a pre-grant to shell for the emergency session
permission.

Test: Run CTS tests to observe presence of security exception.
Bug: 169603138
Change-Id: If8304a741e93bfd60b553239452deeaefddcc04a