According to guide `gpio_stay_*_map` are specifically there to prevent
pulling pins to a specific level and let them float during deep sleep.
https://docs.bekencorp.com/sdk_3.0.x/bk7238/build/en/latest/developer-guide/power_save/sleep_test.html
This allows any external low-power circuitry to change a pin level, as
required, to trigger the wake up
This requires changes in BDK and was implemented via fixup. Also, exposed
`gpio_stay_lo_map` parameter via `lt_deep_sleep_keep_floating_gpio` to
manage this configuration for pins in range P0-P31.
* Initial support code for Deep Sleep
* Global functions
* Remove unnecessary override
* clang-format
* Support for multiple pins
* Fix math
* Add a way to unset GPIOs
* Clang format
* Update brief
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Co-authored-by: Kuba Szczodrzyński <kuba@szczodrzynski.pl>
