spi: dt-bindings: fsl-dspi: add compatible string 'fsl,lx2160a-dspi'

Add compatible string 'fsl,lx2160a-dspi' and allow fall back to
'fsl,ls2085a-dspi'.
Fix below CHECK_DTBS warning.

arch/arm64/boot/dts/freescale/fsl-lx2160a-bluebox3.dtb: spi@2100000: compatible: 'oneOf' conditional failed, one must be fixed:
        ['fsl,lx2160a-dspi', 'fsl,ls2085a-dspi'] is too long
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20240703165931.2325807-2-Frank.Li@nxp.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/spi/fsl,dspi.yaml

@@ -34,6 +34,9 @@ properties:
       - items:
           - const: fsl,ls2080a-dspi
           - const: fsl,ls2085a-dspi
+      - items:
+          - const: fsl,lx2160a-dspi
+          - const: fsl,ls2085a-dspi
 
   reg:
     maxItems: 1