With ioremap_cache being replaced with memremap there is no longer a
guarantee that a mapping will silently fall back to an uncached mapping.
Explicitly use a vanilla ioremap() for this short lived mapping.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Jonathan Buzzard <jonathan@buzzard.org.uk>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>