The zephyr function net_shell_cmd_iface() was removed in zephyr v1.14.0,
therefore the MicroPython zephyr port did not build with newer zephyr
versions when CONFIG_NET_SHELL=y. Replace with a more general
shell_exec() function that can execute any zephyr shell command. For
example:
>>> zephyr.shell_exec("net")
Subcommands:
allocs :Print network memory allocations.
arp :Print information about IPv4 ARP cache.
conn :Print information about network connections.
dns :Show how DNS is configured.
events :Monitor network management events.
gptp :Print information about gPTP support.
iface :Print information about network interfaces.
ipv6 :Print information about IPv6 specific information and
configuration.
mem :Print information about network memory usage.
nbr :Print neighbor information.
ping :Ping a network host.
pkt :net_pkt information.
ppp :PPP information.
resume :Resume a network interface
route :Show network route.
stacks :Show network stacks information.
stats :Show network statistics.
suspend :Suspend a network interface
tcp :Connect/send/close TCP connection.
vlan :Show VLAN information.
websocket :Print information about WebSocket connections.
>>> zephyr.shell_exec("kernel")
kernel - Kernel commands
Subcommands:
cycles :Kernel cycles.
reboot :Reboot.
stacks :List threads stack usage.
threads :List kernel threads.
uptime :Kernel uptime.
version :Kernel version.
Signed-off-by: Maureen Helm <maureen.helm@nxp.com>