Delete bta_sys state machine, freaking finally

the only event left is hardware errors, which is
only valid when in the STARTING or ON state.

change "state" to a boolean whether we care about
hw errors or not

Bug: 159815595
Tag: #refactor
Test: compile & verify basic functions working
Change-Id: Ie1f73bc1343276e86d2b3da70b07adab5f54bb0d