Camera: fix wrong signalStreamFlush call

Sometimes the waitUntilIdle call will finish without RequestThread
sending the signalStreamFlush call down to HAL.
Reset the flag when the wait finishes to avoid a wrong call fired
later when the request thread goes to paused.

Test: CTS on Pixel 3, partner testing
Bug: 162062652
Change-Id: I7c6674860a688f0bc42d4083793514b546cbd65d
2 files changed