drm/amdgpu: Skip put_reset_domain if it doesn't exist

For xgmi sriov, the reset is handled by host driver and hive->reset_domain
is not initialized so need to check if it exists before doing a put.

Signed-off-by: Vignesh Chander <Vignesh.Chander@amd.com>
Reviewed-by: Shaoyun Liu <Shaoyun.Liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>