[PATCH] x86-64: do not use virt_to_page on kernel data address

o virt_to_page() call should be used on kernel linear addresses and not
  on kernel text and data addresses. Swsusp code uses it on kernel data
  (statically allocated swsusp_header).

o Allocate swsusp_header dynamically so that virt_to_page() can be used
  safely.

o I am changing this because in next few patches, __pa() on x86_64 will
  no longer support kernel text and data addresses and hibernation breaks.

Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>