backlight: arcxcnn_bl: Drop of_match_ptr for ID table

The driver will match mostly by DT table (even thought there is regular
ID table) so there is little benefit in of_match_ptr (this also allows
ACPI matching via PRP0001, even though it might not be relevant here).

  drivers/video/backlight/arcxcnn_bl.c:378:34: error: ‘arcxcnn_dt_ids’ defined but not used [-Werror=unused-const-variable=]

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230311173556.263086-2-krzysztof.kozlowski@linaro.org