The commit 8592501828
("net: Remove s_addr/s6_addr defines from in_addr/in6_addr")
did a (welcomed) removal of a #define s_addr for which the SimpleLink
SDK was checking, breaking the socket_offload driver build.
This patch fixes the driver to work with this new, better
s_addr symbol definition.
Signed-off-by: Gil Pitney <gil.pitney@linaro.org>