drm/amdgpu: Keep reset handlers shared

Instead of maintaining a list per device, keep the reset handlers common
per ASIC family. A pointer to the list of handlers is maintained in
reset control.

Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Reviewed-by: Le Ma <le.ma@amd.com>
Reviewed-by: Asad Kamal <asad.kamal@amd.com>
Tested-by: Asad Kamal <asad.kamal@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>