[PATCH v7] platform/x86: hp-wmi: Add multicolor LED support for HP keyboard backlight

[Коненко Андрей Викторович]

From: Edip Hazuri <edip@xxxxxxxxx>

Add support for the HP keyboard RGB backlight found on HP OMEN and
HP Victus laptops. These keyboards expose per-zone RGB control through
WMI commands.

Register multicolor LED class devices for each keyboard zone (up to 4
zones, depending on the keyboard type). Each zone exposes individual
red, green, and blue channels via the multicolor LED subsystem.

Also hardware-initiated brightness changes (e.g. via the keyboard
backlight hotkey, mostly fn+f4) are reported.

The color data is stored in a 128-byte color table managed by the
firmware, with RGB values starting at offset 25, packed sequentially
per zone.

Signed-off-by: Konenko Andrey Viktorovich <admin@xxxxxxxxxx>

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Changes since v6:
 - The LED class device names have been made consistent with the 
documentation, in accordance with patch https://lore.kernel.org/linux-leds/
20260504145434.12746-1-johannes.goede@xxxxxxxxxxxxxxxx/
underscores have been replaced with dashes where indicated.

Changes since v5:
 - LED class device names changed from a number to using a descriptive name 
for each zone.

v4: https://lore.kernel.org/all/20260303084022.7223-3-edip@xxxxxxxxx/

Changes since v4:
 - Fix circular dependencies

Changes since v3:
 - Merge the changes into a single commit

Changes since v1:
 - Fix mentioned style errors
 - Add Kconfig dependencies

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