net: Rename lookup_neigh_params function

Rename lookup_neigh_params to lookup_neigh_parms as the struct is named
neigh_parms and all other functions dealing with the struct carry
neigh_parms in their names.

Signed-off-by: Tobias Klauser <klto@zhaw.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>