drm/amdkfd: debugfs hang_hws skip GPU with MES

debugfs hang_hws is used by GPU reset test with HWS, for MES this crash
the kernel with NULL pointer access because dqm->packet_mgr is not setup
for MES path.

Skip GPU with MES for now, MES hang_hws debugfs interface will be
supported later.

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