sparc64: fix direct access to irq_desc

GENERIC_HARDIRQS_NO_DEPRECATED require us to access data via irq_data.
No functional changes as data has same layout due to use of union

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>