ice: xsk: Stop Rx processing when ntc catches ntu

This can happen with big budget values and some breakage of re-filling
descriptors as we do not clear the entry that ntu is pointing at the end
of ice_alloc_rx_bufs_zc. So if ntc is at ntu then it might be the case
that status_error0 has an old, uncleared value and ntc would go over
with processing which would result in false results.

Break Rx loop when ntc == ntu to avoid broken behavior.

Fixes: 3876ff52

 ("ice: xsk: Handle SW XDP ring wrap and bump tail more often")
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220328142123.170157-4-maciej.fijalkowski@intel.com