Remove check that phone or carrier app can call SmsComplete callback

In case of binding failure for example, it is called on the binder
thread. Moreover, there is no real scenario that it can be called
by anyone else, it was added as a safely check in the original CL
ag/631490

Test: manual
Bug: 172839671
Change-Id: I4277456bf574aec89c32759b8331789612e1eb86