net: lwip: dhcp: make NTP servers usable by the sntp command

When both CMD_DHCP and CMD_SNTP are enabled, one would expect the NTP
servers received by DHCP to be used by the sntp command by default. Fix
dhcp_loop() so that it is indeed the case.

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Reported-by: Michal Simek <michal.simek@amd.com>

net/lwip/dhcp.c

diff --git a/net/lwip/dhcp.c b/net/lwip/dhcp.c
index 4c9cb0e..cbdfea3 100644
--- a/net/lwip/dhcp.c
+++ b/net/lwip/dhcp.c
@@ -8,6 +8,7 @@
 #include <dm/device.h>
 #include <linux/delay.h>
 #include <linux/errno.h>
+#include <lwip/apps/sntp.h>
 #include <lwip/dhcp.h>
 #include <lwip/dns.h>
 #include <lwip/timeouts.h>
@@ -48,6 +49,13 @@
 	if (!netif)
 		return CMD_RET_FAILURE;
 
+	/*
+	 * Request the DHCP stack to parse and store the NTP servers for
+	 * eventual use by the SNTP command
+	 */
+	if (CONFIG_IS_ENABLED(CMD_SNTP))
+		sntp_servermode_dhcp(1);
+
 	start = get_timer(0);
 
 	if (dhcp_start(netif))