asmlinkage: Make __iowrite32_copy visible

This is a assembler function on x86, so it should be visible.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1391845930-28580-2-git-send-email-ak@linux.intel.com


Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>