UCP/WIREUP: Fix stub_ep error flow - need to reset next_ep to NULL.
UCP/WIREUP: Fix stub_ep error flow - need to reset next_ep to NULL.

sergsagal1/ucx_rocm,shssf/ucx,shssf/ucx,sergsagal1/ucx_rocm,shssf/ucx,sergsagal1/ucx_rocm