KConfig vs NVS configuration

[mutatrum]

Currently, some settings are configured via KConfig, and some via the NVS partition. The first requires a custom firmware, the second can be done either through a firmware flash with a config.cvs or through the configurations page if it's built into AxeOS. When #380 is added, the NVS values could also be set directly.

KConfig	NVS	AxeOS	Remark
	boardversion		In future from eFuse
	devicemodel		derived from boardversion
	asicmodel		derived from boardversion
ASIC_FREQUENCY	asicfrequency	Settings
ASIC_VOLTAGE	asicvoltage	Settings
	autofanspeed	Settings
	fanspeed	Settings
	temptarget	Settings
STRATUM_URL	stratumurl	Pool settings
STRATUM_PORT	stratumport	Pool settings
FALLBACK_STRATUM_URL	fbstratumurl	Pool settings
FALLBACK_STRATUM_PORT	fbstratumport	Pool settings
STRATUM_USER	stratumuser	Pool settings
STRATUM_PW	stratumpass	Pool settings
FALLBACK_STRATUM_USER	fbstratumuser	Pool settings
FALLBACK_STRATUM_PW	fbstratumpass	Pool settings
	wifissid	Network
	wifipass	Network
	hostname	Network
	display	Settings -> Display
	flipscreen	Settings -> Display
	invertscreen	Settings -> Display
	displayTimeout	Settings -> Display
	statsLimit	Settings -> Statistics
	statsDuration	Settings -> Statistics
	themescheme	Customization
	themecolors	Customization
	bestdiff		Only from firmware
	selftest		Or with BOOT button on startup
	overheat_mode	Dashboard	Disable only
	oc_enabled	?oc
	swarmconfig	Swarm
GPIO_BUTTON_BOOT
GPIO_ASIC_RESET
GPIO_ASIC_ENABLE
GPIO_PLUG_SENSE
GPIO_I2C_SDA
GPIO_I2C_SCL
STRATUM_DIFFICULTY

This is a bit of a disjoint set of possibilities. I'm not sure if the KConfig values are used anywhere, as this would mean it's only usable with a custom firmware.

As for a lot of NVS values, the defaults are now in the config.cvs files, to simplify the code they could be moved into the firmware.

Is there merit in moving away from KConfig and defaults in NVS? Some arguments were also mentioned in #716, but this adds the extra layer of KConfig.