remove remaining crash_notes definition to fix compile error

/dev/shm/linux-2.6/arch/powerpc/kernel/machine_kexec.c:21: error: conflicting types for `crash_notes'
/dev/shm/linux-2.6/include/linux/kexec.h:129: error: previous declaration of `crash_notes'
Signed-off-by: Olaf Hering <olh@suse.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>