x86: remove debug printks (io_apic.c)

Impact: reduce printk noise

The message "alloc irq_2_pin on cpu 0 node 0" is printed way too often.

% dmesg|grep irq_2_pin|wc -l
20

Get rid of the debug printks.

Signed-off-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>