to be more self-contained and only return success if streaming indeed
successfully was turned on at the sensor. It's also the only place
that sets the "streaming" state to 1. This simplifies error handling.

Background to the register reading we're moving up so that enabling
streaming is the last operation:

Reading 0x0034 is purely done for debugging reasons. The register is not
documented in the DS but only mentioned once:

"If 0x0034[2] bit is disabled , Visible pixel width and height is 0."

I've never seen that bit be disabled.