Since devicetree nodes are (sometimes?) processed in reverse order,
support reg as the actual multi_index index so yo get well defined
color order presented in the multi_index file.
Not sure if reusing reg for this is the correct way or if another
property such as "multi_index" or similar should be used instead.
Looks like reg is used for similar things at least.
Or should the whole "reverse the devicetree" problem be fixed instead?
Update bindings to match implementation, and add description for the
reg property.

Signed-off-by: Johan Adolfsson <redacted>
---
Changes in v7:
- Skip leftover initialization of multi_index.
- Fix devcietree description and update commit message.
- Link to v6: https://lore.kernel.org/r/20250616-led-fix-v6-0-b9df5b63505d@axis.com (local)

Changes in v6:
- Remove maxItems från devicetree binding
- Link to v5: https://lore.kernel.org/r/20250616-led-fix-v5-0-f59c740831ab@axis.com (local)

Changes in v5:
- Fail if reg is not set.
- Adjust devicetree schema, use items.
- Link to v4: https://lore.kernel.org/r/20250526-led-fix-v4-0-33345f6c4a78@axis.com (local)

Changes in v4:
- Remove maxItems from devicetree schema, not compatible with minimum
  and maximum.
- Link to v3: https://lore.kernel.org/r/20250523-led-fix-v3-0-86d2690d2698@axis.com (local)

Changes in v3:
- Update To and Cc.
- Rephrase bindings descriptions, add constraints.
- Link to v2: https://lore.kernel.org/r/20250522-led-fix-v2-0-652046323ec3@axis.com (local)

Changes in v2:
- Avoid duplicate assignment. dev_err and return -EINVAL on error.
- Update bindings doc.
- Link to v1: https://lore.kernel.org/r/20250506-led-fix-v1-1-56a39b55a7fc@axis.com (local)

---
Johan Adolfsson (2):
      leds: leds-lp50xx: Handle reg to get correct multi_index
      dt-bindings: leds: lp50xx: Document child reg, fix example

 .../devicetree/bindings/leds/leds-lp50xx.yaml         | 19 ++++++++++++-------
 drivers/leds/leds-lp50xx.c                            | 11 ++++++++++-
 2 files changed, 22 insertions(+), 8 deletions(-)
---
base-commit: 0ff41df1cb268fc69e703a08a57ee14ae967d0ca
change-id: 20250225-led-fix-444fb544584a

Best regards,
-- 
Johan Adolfsson [off-list ref]