ARM: uniphier: add macro to generate SoC data look-up function

ARM: uniphier: add macro to generate SoC data look-up function

There are similar functions that look up SoC data by the SoC ID.
The new macro UNIPHIER_DEFINE_SOCDATA_FUNC will be helpful to
avoid the code duplication.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>