net/smc911x: fix return from smc911x_send

return value of smc911x_send is ignored, but on sucesseful
send we need return 0 and or error -ETIMEOUT, not opposite.

Signed-off-by: Maxim Uvarov <maxim.uvarov@linaro.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>