drm/amdgpu: Add reset_list for device list used for reset

The gmc.xgmi.head list originally is designed for device list in the XGMI hive. Mix use it
for reset purpose will prevent the reset function to adjust XGMI device list which is required
in next change

Signed-off-by: shaoyunl <shaoyun.liu@amd.com>
Reviewed-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>