dt-bindings: serial: 8250: Remove duplicated compatible strings

dt-bindings: serial: 8250: Remove duplicated compatible strings

commit a7277a73984114b38dcb62c8548850800ffe864e upstream.

The compatible strings "mediatek,*" appears two times, remove one of them.

Fixes: e69f5dc623f9 ("dt-bindings: serial: Convert 8250 to json-schema")
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/r/20210422090857.583-1-thunder.leizhen@huawei.com
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>