platform/x86/amd: Introduce Halo Box RGB LED driver

The Halo Box features an RGB LED light bar that can be controlled
through WMI methods to display any color combination.

The driver exposes the LED through the LED multicolor subsystem,
allowing userspace to control RGB values via sysfs:
  /sys/class/leds/amd_halo:multicolor:status/multi_intensity
  /sys/class/leds/amd_halo:multicolor:status/brightness

Hardware interface:
- Three separate RGB channels (Red, Green, Blue)
- All 3 channels are configured at once with a single WMI method call
- Value range: 0-100 (matching hardware range directly)

Co-developed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
Reviewed-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Reviewed-by: Armin Wolf <W_Armin@gmx.de>
Signed-off-by: Yo-Jung Leo Lin (AMD) <Leo.Lin@amd.com>
Link: https://patch.msgid.link/20260709-halo-leds-v2-plus-v8-1-b34c64277193@amd.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

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