[IA64] Fix kernel panic in kdump on INIT

Fix the problem that kdump on INIT causes a kernel panic if kdump
kernel image is not configured. The cause of this problem is
machine_kexec_on_init() is using printk in INIT context. It should
use ia64_mca_printk() instead.

Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>