net: ethernet: ti: cpts: break cycle once late ts is matched

The late ts queue can contain a bunch of skbs while hi rate testing,
no need to check all of them if timestamp is already matched.

Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>