sh: Merge _32/_64 ioremap implementations.

There is nothing of interest in the _64 version anymore, so the _32 one
can be renamed and used unconditionally.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

diff --cc arch/sh/mm/Makefile
Simple merge

diff --cc arch/sh/mm/ioremap.c
Simple merge

diff --cc arch/sh/mm/ioremap_64.c
Simple merge