Merge branch 'bugfix/bootloader_disable_sar_test_mux' into 'master'

Deep sleep fixes

This change fixes extra 24 uA current consumption in deep sleep mode (https://esp32.com/viewtopic.php?f=2&t=1133).

Recent update to libphy/librtc caused another problem that WiFi related parts of RTC are no longer disabled by RTC sleep functions. This means that if WiFi is not disabled by the application before entering deep sleep, extra ~200uA of current would be consumed. This is fixed, and documentation for esp_deep_sleep and SNTP example are updated to mention that applications should take care of disabling WiFi and BT before going into the deep sleep mode.

See merge request !516