Some of the esp_sntp_...() APIs that wrap lwip's SNTP
module use tcpip_callback() to execute the lwip functionality
in the correct state (either with locked TCP/IP core,
or within the TCP/IP thread).
tcpip_callback() however doesn't wait for completion of the callback,
which doesn't prevent from using the stack variables after destroy
if used as a parameter.
Introduced in a71fa82.
Fixed by using of tcpip_api_call() instead of the tcpip_callback().
Closes https://github.com/espressif/esp-idf/issues/10611
