fix: turn off T-Echo peripherals on deep sleep

[andrekir]

turn off peripherals before deep sleep (fixes #1493)

similar to RAK's PIN_3V3_EN, we need to enable in setup() and disable before deep sleep/shutdown.

• PIN_POWER_EN (0,12);
• PIN_POWER_EN1 (0,13) (undocumented but references in LilyGO's T-Echo's GitHub repo and SoftRF).

also:

• renames PIN_EINK_PWR_ON to PIN_POWER_EN to match LilyGO's pin map.
• removes T-Echo peripheral power on from EInkDisplay2

[andrekir]

@pista01 can you please test the .uf2 in the zip below and check if your T-Echo works without the boot loop issue?

--> https://github.com/meshtastic/firmware/actions/runs/8115521375/artifacts/1290267299

[pista01]

Sorry, just saw this. Installed the uf2. The reboots are back now.

[andrekir]

@pista01 good to know, thanks for testing!