HdmiCecControl: Fix bad state if press_and_hold keydown fails
HdmiCecControl: Fix bad state if press_and_hold keydown fails

If the initial keydown fails, we thought we were in the "sending
keydowns every 300ms" state, but we hadn't actually started the thread
to do so. The only way to get out of this state is to call `keyup`.

stb-tester/stb-tester,stb-tester/stb-tester,stb-tester/stb-tester,stb-tester/stb-tester