test/py: IPv6 network discovery test

Test the IPv6 network discovery feature if indicated by boardenv file.

Signed-off-by: Ehsan Mohandesi <emohandesi@linux.microsoft.com>
Reviewed-by: Viacheslav Mitrofanov <v.v.mitrofanov@yadro.com>
diff --git a/configs/sandbox64_defconfig b/configs/sandbox64_defconfig
index f5cfdc4..f3002de 100644
--- a/configs/sandbox64_defconfig
+++ b/configs/sandbox64_defconfig
@@ -69,6 +69,7 @@
 CONFIG_CMD_SNTP=y
 CONFIG_CMD_DNS=y
 CONFIG_CMD_LINK_LOCAL=y
+CONFIG_IPV6_ROUTER_DISCOVERY=y
 CONFIG_CMD_ETHSW=y
 CONFIG_CMD_BMP=y
 CONFIG_CMD_EFIDEBUG=y
diff --git a/configs/sandbox_defconfig b/configs/sandbox_defconfig
index b775bf5..1ec44d5 100644
--- a/configs/sandbox_defconfig
+++ b/configs/sandbox_defconfig
@@ -101,6 +101,7 @@
 CONFIG_CMD_SNTP=y
 CONFIG_CMD_DNS=y
 CONFIG_CMD_LINK_LOCAL=y
+CONFIG_IPV6_ROUTER_DISCOVERY=y
 CONFIG_CMD_ETHSW=y
 CONFIG_CMD_2048=y
 CONFIG_CMD_BMP=y
diff --git a/configs/sandbox_flattree_defconfig b/configs/sandbox_flattree_defconfig
index 5b6b28a..e7657d4 100644
--- a/configs/sandbox_flattree_defconfig
+++ b/configs/sandbox_flattree_defconfig
@@ -59,6 +59,7 @@
 CONFIG_CMD_SNTP=y
 CONFIG_CMD_DNS=y
 CONFIG_CMD_LINK_LOCAL=y
+CONFIG_IPV6_ROUTER_DISCOVERY=y
 CONFIG_CMD_EFIDEBUG=y
 CONFIG_CMD_RTC=y
 CONFIG_CMD_TIME=y