Dmitry Kasatkin reports:
"kernel-devel package with kernel headers have no <include/xen>
directory if XEN is disabled. Modules which inclide asm/io.h won't
compile.
XEN related content is behind the CONFIG_XEN flag in the io.h. And
<xen/xen.h> should be also behind CONFIG_XEN flag."
So move the include of <xen/xen.h> down into the section that is
conditional on CONFIG_XEN.
Reported-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>