drm/amdgpu/kfd: remove is_hws_hang and is_resetting

is_hws_hang and is_resetting serves pretty much the same purpose and
they all duplicates the work of the reset_domain lock, just check that
directly instead. This also eliminate a few bugs listed below and get
rid of dqm->ops.pre_reset.

kfd_hws_hang did not need to avoid scheduling another reset. If the
on-going reset decided to skip GPU reset we have a bad time, otherwise
the extra reset will get cancelled anyway.

remove_queue_mes forgot to check is_resetting flag compared to the
pre-MES path unmap_queue_cpsch, so it did not block hw access during
reset correctly.

Signed-off-by: Yunxiang Li <Yunxiang.Li@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>