Convert the UniPhier I2C controller (FIFO-less) binding to DT schema
format.

There are two types of I2C controllers used on the UniPhier platform.
This is the legacy one without FIFO support, which is used on the
sLD8 SoC or older.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Rob Herring <robh@kernel.org>