In the next commit, I will have more usecases to get struct image_info
from image ID.  It is better to make a helper function at a different
layer.  I do not need the current uniphier_image_descs_fixup() since
the code is small enough to be squashed into the caller side.

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

Initial commit for Socionext UniPhier SoC support.  BL1, Bl2, and
BL31 are supported.  Refer to docs/plat/socionext-uniphier.md for
more detais.

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