fwk: KB auto brightness just one low level

You only need KB backlight if the environment is extremely dim and your
keyboard is not illuminated.
Even sometimes when you're in a fully dark room and you turn up your
display brightness, if reflects off the environment and lights up the
keyboard enough to see it.

BUG=Backlight brightness sometimes toggles back and forth because
there's no hysteresis. It doesn't need that many levels. And it doesn't
need to be on when there's environmental light.
BRANCH=fwk-main
TEST=FN+SPACE to toggle kb backlight brightness to auto. You'll see
backlight off, unless the environment is very dark (so dark you can't
see the keycap labels)

Signed-off-by: Daniel Schaefer <dhs@frame.work>
(cherry picked from commit 5ecaaaa)

Author: JohnAZoidberg

zephyr/program/framework/src/led.c

@@ -218,14 +218,8 @@ void auto_als_led_brightness(void)
 
 #ifdef CONFIG_PLATFORM_EC_KEYBOARD
 	if (kbbl_auto_dim_is_enable()) {
-		if (als_lux > 130)
-			kb_brightness = KEYBOARD_BL_BRIGHTNESS_HIGH;
-		else if (als_lux > 100)
-			kb_brightness = KEYBOARD_BL_BRIGHTNESS_MED;
-		else if (als_lux > 70)
-			kb_brightness = KEYBOARD_BL_BRIGHTNESS_MED_LOW;
-		else if (als_lux > 40)
-			kb_brightness = KEYBOARD_BL_BRIGHTNESS_LOW;
+		if (als_lux > 5)
+			kb_brightness = KEYBOARD_BL_BRIGHTNESS_OFF;
 		else
 			kb_brightness = KEYBOARD_BL_BRIGHTNESS_ULT_LOW;