x86/irq: Use accessor irq_data_get_irq_handler_data()

Use accessor function irq_data_get_irq_handler_data() to hide irq_desc
implementation details.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>