[IA64] fix non-numa build

arch/ia64/kernel/machine_kexec.c: In function `arch_crash_save_vmcoreinfo':
arch/ia64/kernel/machine_kexec.c:131: error: `pgdat_list' undeclared (first use in this function)
arch/ia64/kernel/machine_kexec.c:131: error: (Each undeclared identifier is reported only once
arch/ia64/kernel/machine_kexec.c:131: error: for each function it appears in.)
arch/ia64/kernel/machine_kexec.c:134: error: `node_memblk' undeclared (first use in this function)
arch/ia64/kernel/machine_kexec.c:135: error: `NR_NODE_MEMBLKS' undeclared (first use in this function)
arch/ia64/kernel/machine_kexec.c:136: error: invalid application of `sizeof' to incomplete type `node_memblk_s'
arch/ia64/kernel/machine_kexec.c:137: error: dereferencing pointer to incomplete type
arch/ia64/kernel/machine_kexec.c:138: error: dereferencing pointer to incomplete type
make[1]: *** [arch/ia64/kernel/machine_kexec.o] Error 1

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>