Replace printf() with proper ESP_LOGx() (CA-137)

[liudr]

There are several printf() in the port folder. Here is one example:

esp-azure/port/src/agenttime_esp.c

Line 15 in 90716c7

printf("Initializing SNTP\n");

I recommend replacing them with appropriate ESP_LOGx() to help control log level. Especially if someone wants a clean console app and azure keeps printing out waiting for time etc.

Thanks.