dt-bindings: iio: magnetometer: asahi-kasei,ak8975: Drop deprecated enums

Drop deprecated enums from bindings as it is been here for a long time.
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20230818075600.24277-4-biju.das.jz@bp.renesas.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/magnetometer/asahi-kasei,ak8975.yaml

@@ -18,13 +18,6 @@ properties:
           - asahi-kasei,ak09911
           - asahi-kasei,ak09912
           - asahi-kasei,ak09916
-      - enum:
-          - ak8975
-          - ak8963
-          - ak09911
-          - ak09912
-          - ak09916
-        deprecated: true
 
   reg:
     maxItems: 1