Revert "of/platform: export of_default_bus_match_table"

This reverts commit b80443c2.

After covering to use helper of_platform_default_populate() to populate
the default bus, no need to export of_default_bus_match_table anymore.

Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: Grant Likely <grant.likely@linaro.org>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Rob Herring <robh@kernel.org>