[PATCH] x86_64: remove unusued 'flags' variable

Removes unused 'flags' variable from setup_IO_APIC_irq().

Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>