Telephony: Reduce back to back same APN activation delay.

- The default delay to activate same APN in quick succession is
  20 seconds.
- Some application like embms may want to activate APN quickly
  in short burst. Current 20 seconds would result in artificial
  delays in such applications.
- Hence changing the default delay value to be equivalent of
  fail-fast delay which is 3 seconds.

Change-Id: I792c9697e8ff2d90ec0e9bf2fda8ccf1b3dd9074