mmc: uniphier-sd: Update the file to match V3 patchset

Old version of the uniphier-sd 64bit IO support patchset V1 was
applied by the maintainer, update the uniphier-sd.c with the
changes from the V3 of the patchset.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Jaehoon Chung <jh80.chung@samsung.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>