LinuxKPI: Define ioread64() in linux/io.h only on 64 bit archs.
32 bit archs includes nonatomic version from linux/io-64-nonatomic-*.h
Sponsored by: Serenity Cyber Security, LLC
Fixes: dcfc983373c3 ("LinuxKPI: Implement ioread64()")
MFC after: 1 week
(cherry picked from commit 73ccd188c43a6cd52a12ac33411896220b2d2e54)