sane irq initialization in sedlbauer hisax

The interrupts schould be disabled until the driver
is ready and the IRQ function was registered.

Thanks to Bastian Friedrich  and Thomas Voegtle for spotting this.

Signed-off-by: Karsten Keil <kkeil@suse.de>
Signed-off-by: Bastian Friedrich <bastian@bastian-friedrich.de>
Signed-off-by: Thomas Voegtle <tv@lio96.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>