Fixed device crash on automation setup

This is a regression introduced by
https://android-review.googlesource.com/#/c/342381/
Sending the broadcast intent twice (extra one is for sl4a) causes
EVENT_BROADCAST_COMPLETE got sent twice, which brought the wake lock
state machine into the bad state.

Fixed by changing the first result receiver to null so only one
EVENT_BROADCAST_COMPLETE will be broadcasted.

Test: Telephony sanity tests
bug: 36107224
Change-Id: I02b4b4b9fa7a3106ad83e0200cf1e6dc5924c771