ia64: cpumask fix for is_affinity_mask_valid()

Impact: build fix on ia64

ia64's default_affinity_write() still had old cpumask_t usage:

 /home/mingo/tip/kernel/irq/proc.c: In function `default_affinity_write':
 /home/mingo/tip/kernel/irq/proc.c:114: error: incompatible type for argument 1 of `is_affinity_mask_valid'
 make[3]: *** [kernel/irq/proc.o] Error 1
 make[3]: *** Waiting for unfinished jobs....

update it to cpumask_var_t.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/ia64/kernel/irq.c b/arch/ia64/kernel/irq.c
index 0b6db53..95ff16c 100644
--- a/arch/ia64/kernel/irq.c
+++ b/arch/ia64/kernel/irq.c
@@ -112,11 +112,11 @@
 	}
 }
 
-bool is_affinity_mask_valid(cpumask_t cpumask)
+bool is_affinity_mask_valid(cpumask_var_t cpumask)
 {
 	if (ia64_platform_is("sn2")) {
 		/* Only allow one CPU to be specified in the smp_affinity mask */
-		if (cpus_weight(cpumask) != 1)
+		if (cpumask_weight(cpumask) != 1)
 			return false;
 	}
 	return true;