drm/amdkfd: Trap handler changes for GC 9.4.3 v2

v1:
Check new exception bits in TRAPSTS register
Remove single step exception workaround, now part of
exception bits

v2:
GC 9.4.3 uses ttmp11 to store {1’b0, dispatch index [24:0],
wave_id_in_workgroup[5:0]}, so use ttmp13 instead of ttmp11 to
preserve ib_sts. (Laurent)

Signed-off-by: Jay Cornwall <jay.cornwall@amd.com>
Signed-off-by: Laurent Morichetti <Laurent.Morichetti@amd.com>
Reviewed-by: Laurent Morichetti <laurent.morichetti@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>