Before we did some clever tricks to not use the a lock when touching
guc_state.sched_state in certain cases. Don't do that, enforce the use
of the lock.

v2:
 (kernel test robo )
  - Add __maybe_unused to sched_state_is_init()

v3: rebase after the unused code path removal has been moved to an
earlier patch.
Signed-off-by: NMatthew Brost <matthew.brost@intel.com>
Reported-by: Nkernel test robot <lkp@intel.com>
Reviewed-by: NDaniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: NJohn Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210909164744.31249-14-matthew.brost@intel.com