ia64: Remove superfluous SMP function call

Since commit 3b9d6da6 ("cpu/hotplug: Fix rollback during error-out
in __cpu_disable()") it is ensured that callbacks of CPU_ONLINE and
CPU_DOWN_PREPARE are processed on the hotplugged CPU. Due to this SMP
function calls are no longer required.

Replace smp_call_function_single() with a direct call to
ia64_mca_cmc_vector_adjust(). The function itselfs handles disable and
enable interrupts, therefore the smp_call_function_single() calling
convention is not preserved.

Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: linux-ia64@vger.kernel.org
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Tony Luck <tony.luck@intel.com>