[PATCH] do_IRQ() warning fix

arch/i386/kernel/irq.c: In function 'do_IRQ':
arch/i386/kernel/irq.c:104: warning: suggest parentheses around arithmetic in operand of |

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>