Fix deepsleep issues

[ElGuzo]

#4 #8 #2 Deepsleep is not working probably. Waking up always after 3 seconds.

[gpayer]

Thank you for your fix! Unfortunately all your changes were never merged, so deep sleep still doesn't work when USB is connected. I used your code to write my own shutdown function and now it works both in battery and in USB mode.

[stephankoelle]

For me that pull request was not needed, I looks like deepsleep was fix some other way.

[xlla]

the boost circuit maybe consume more current than esp_in_deep_sleep, so it is useless for deepsleep attempt.