Added a cast to esp_sntp_operatingmode_t in sntp_setoperatingmode()'s
call to esp_sntp_setoperatingmode(operating_mode). Althouogh C
doesn't require the cast, C++ does. Otherwise you get...
error: invalid conversion from 'u8_t' {aka 'unsigned char'}
to 'esp_sntp_operatingmode_t'
This commit updates the chip independent system chapters of the
programming guide for esp32s3.
Signed-off-by: Sudeep Mohanty <sudeep.mohanty@espressif.com>