drm/amdkfd: Fix DQM asserts on Hawaii

start_nocpsch would never set dqm->sched_running on Hawaii due to an
early return statement. This would trigger asserts in other functions
and end up in inconsistent states.

Bug: https://github.com/RadeonOpenCompute/ROCm/issues/1624


Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Kent Russell <kent.russell@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>