net: flow_offload: correct comments mismatch with code

Correct mismatch between the name of flow_offload_has_one_action()
and its kdoc entry.

Found using ./scripts/kernel-doc -Werror -none include/net/flow_offload.h

Signed-off-by: Bijie Xu <bijie.xu@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>