drm/amd/display: Fix crash on device remove/driver unload

Why:
DC core is being released from DM before it's referenced
from hpd_rx wq destruction code.

How: Move hpd_rx destruction before DC core destruction.

Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>