I8K: allow i8k driver to be built on x86_64 systems

Adds #if clause and additional inline assembly so that the driver
builds on x86_64 systems.

Signed-off-by: Bradley Smith <bradjsmith@btinternet.com>
Cc: Frank Sorenson <frank@tuxrocks.com>
Cc: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>