CAM - Fix missing SIM lock in cam_periph_release()

CAM - Fix missing SIM lock in cam_periph_release()

* When releasing the last reference on a CAM peripheral which has been
  marked invalid, the peripheral is then freed.  Freeing the peripheral
  requires the SIM lock.

  Go through necessary tribulations to acquire the SIM lock.  The lock order
  is important (SIM lock first, XPT lock second), and the SIM lock may or
  may not already be held by the thread.

* The bug could cause a crash after burning a CD as the CD becomes invalid
  after the burn completes in order to reload its state.