[PATCH] kdump: export per cpu crash notes pointer through sysfs

- Kexec on panic functionality allocates memory for saving cpu registers in
  case of system crash event.  Address of this allocated memory needs to be
  exported to user space, which is used by kexec-tools.

- Previously, a single /sys/kernel/crash_notes entry was being exported as
  memory allocated was a single continuous array.  Now memory allocation being
  dyanmic and per cpu based, address of per cpu buffer is exported through
  "/sys/devices/system/cpu/cpuX/crash_notes"

Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>