cpumask: Remove mask field from comments

By 7be23e278f, mask field was deleted by irqaction. However, it was not
deleted from comment.

Signed-off-by: Nobuhiro Iwamatsu <iwamatsu.nobuhiro@renesas.com>
CC: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

include/linux/interrupt.h

@@ -84,7 +84,6 @@ typedef irqreturn_t (*irq_handler_t)(int, void *);
  * struct irqaction - per interrupt action descriptor
  * @handler:	interrupt handler function
  * @flags:	flags (see IRQF_* above)
- * @mask:	no comment as it is useless and about to be removed
  * @name:	name of the device
  * @dev_id:	cookie to identify the device
  * @next:	pointer to the next irqaction for shared interrupts