dt-bindings: mfd: fsl,mc13xxx: Fix LEDs node schema

dt-bindings: mfd: fsl,mc13xxx: Fix LEDs node schema

The 'leds' node is missing constraints on additional properties. It is
mixing 'leds' node and child node properties as well as missing some
properties. Add the 'led@' child nodes and the missing properties.

Fixes: 1160f9f88be2 ("dt-bindings: mfd: fsl,mc13xxx: Convert txt to DT schema")
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20251118213541.43812-1-robh@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>