samples: openthread: fix kconfig build warning

Fix Kconfig warnings by dropping NET_L2_IEEE802154_SHELL from the
OpenThread sample. This option depends on CONFIG_NET_L2_IEEE802154,
which is not selected in the sample, causing unmet dependency warnings.

Removing it lets the sample build cleanly without extra config noise.

Signed-off-by: Sylvio Alves <[email protected]>

Author: sylvioalves

samples/net/openthread/shell/prj.conf

@@ -18,4 +18,3 @@ CONFIG_NET_LOG=y
 CONFIG_SHELL=y
 CONFIG_NET_SHELL=y
 CONFIG_OPENTHREAD_SHELL=y
-CONFIG_NET_L2_IEEE802154_SHELL=y