tests: socket_helpers: Use zsock_ prefixed socket functions
tests: socket_helpers: Use zsock_ prefixed socket functions

Don't depend on CONFIG_NET_SOCKETS_POSIX_NAMES being defined (e.g.,
it's going to conflict with POSIX API).

Signed-off-by: Paul Sokolovsky <35cb557f011771c94f127d6fef99f804b62203f5@linaro.org>

GiulianoFranchetto/zephyr,Vudentz/zephyr,galak/zephyr,ldts/zephyr,galak/zephyr,ldts/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,GiulianoFranchetto/zephyr,finikorg/zephyr,GiulianoFranchetto/zephyr,ldts/zephyr,finikorg/zephyr,ldts/zephyr,nashif/zephyr,Vudentz/zephyr,GiulianoFranchetto/zephyr,nashif/zephyr,nashif/zephyr,finikorg/zephyr,GiulianoFranchetto/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,Vudentz/zephyr,galak/zephyr,galak/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,ldts/zephyr,finikorg/zephyr,nashif/zephyr