Fix [issue VSChina#12](VSChina#12) and [issue 18](VSChina#18)

beegee-tokyo · beegee-tokyo · commit f6d59b756804 · 2019-10-23T10:48:03.000+08:00
```
assertion "Operating mode must not be set while SNTP client is running" failed: file "/home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/lwip/lwip/src/apps/sntp/sntp.c", line 600, function: sntp_setoperatingmode
```    
`SNTP_Deinit();` required before `sntp_setoperatingmode(SNTP_OPMODE_POLL);` if SNTP was initialized already.
diff --git a/src/az_iot/c-utility/pal/lwip/sntp_lwip.c b/src/az_iot/c-utility/pal/lwip/sntp_lwip.c
@@ -36,6 +36,7 @@ int SNTP_SetServerName(const char* serverName)
 int SNTP_Init()
 {
 	LogInfo("Initializing SNTP");
+	SNTP_Deinit();
 	sntp_setoperatingmode(SNTP_OPMODE_POLL);
 	sntp_init();
 	time_t ts = 0;

Original file line number	Diff line number	Diff line change
`@@ -36,6 +36,7 @@ int SNTP_SetServerName(const char* serverName)`
`36`	`36`	`int SNTP_Init()`
`37`	`37`	`{`
`38`	`38`	`LogInfo("Initializing SNTP");`
	`39`	`+ SNTP_Deinit();`
`39`	`40`	`sntp_setoperatingmode(SNTP_OPMODE_POLL);`
`40`	`41`	`sntp_init();`
`41`	`42`	`time_t ts = 0;`