dt-bindings: nvmem: fixed-layout: Allow optional bit positions

NVMEM nodes can optionally include the bits property to specify the bit
position of the cell within a byte.
Extend patternProperties to allow adding the bit offset to the node
address to be able to distinguish nodes with the same address but
different bit positions, e.g.

   trim@54,4 {
        reg = <0x54 1>;
        bits = <4 2>;
    };
    trim@54,0 {
        reg = <0x54 1>;
        bits = <0 4>;
    };

Before the conversion to NVMEM layouts in commit bd912c9
("dt-bindings: nvmem: layouts: add fixed-layout") this extension was
originally added with commit 4b2545d ("dt-bindings: nvmem: Extend
patternProperties to optionally indicate bit position") to the now
deprecated layout.

Signed-off-by: Sven Peter <sven@kernel.org>
Reviewed-by: "Rob Herring (Arm)" <robh@kernel.org>
Signed-off-by: Srinivas Kandagatla <srini@kernel.org>
Link: https://lore.kernel.org/r/20250712181905.6738-3-srini@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: svenpeter42

Documentation/devicetree/bindings/nvmem/layouts/fixed-layout.yaml

@@ -27,7 +27,7 @@ properties:
     const: 1
 
 patternProperties:
-  "@[a-f0-9]+$":
+  "@[a-f0-9]+(,[0-7])?$":
     type: object
     $ref: fixed-cell.yaml
     unevaluatedProperties: false