ia64: cpumask fix for is_affinity_mask_valid()

Impact: cleanup

The function prototype should use 'struct cpumask *' to declare
cpumask arguments (instead of cpumask_var_t).

Note: arch/ia64/kernel/irq.c still had the following "old cpumask_t" usages:

105:	cpumask_t mask = CPU_MASK_NONE;
107:	cpu_set(cpu_logical_id(hwid), mask);
110:                 irq_desc[irq].affinity = mask;

	... replaced with a simple "cpumask_of(cpu_logical_id(hwid))".

161:			new_cpu = any_online_cpu(cpu_online_map);
194:		time_keeper_id = first_cpu(cpu_online_map);

	... replaced with cpu_online_mask refs.

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>