zephyr: Disable CONFIG_NET_SOCKETS_POSIX_NAMES.

Zephyr's default value for CONFIG_NET_SOCKETS_POSIX_NAMES was changed
from false to true between Zephyr v2.5.0 and v2.6.0. This caused
conflicts in MicroPython, which uses the zsock_ prefixed functions, so
disable it.

Signed-off-by: Maureen Helm <maureen.helm@nxp.com>

ports/zephyr/prj.conf

@@ -26,6 +26,7 @@ CONFIG_NET_IPV6=y
 CONFIG_NET_UDP=y
 CONFIG_NET_TCP=y
 CONFIG_NET_SOCKETS=y
+CONFIG_NET_SOCKETS_POSIX_NAMES=n
 CONFIG_TEST_RANDOM_GENERATOR=y
 
 CONFIG_NET_CONFIG_SETTINGS=y