x86/irq: Correct comment about i8259 initialization

0x30-0x3f have been used for ISA interrupts on i386 as well
since 5 years ago, but old comments about i8259 initialization
were still referring to the old i386 usage of this port range.

Signed-off-by: Yanchuan Nian <ycnian@gmail.com>
Cc: yinghai@kernel.org
Cc: pavel@suse.cz
Link: http://lkml.kernel.org/r/1378257924-29446-1-git-send-email-ycnian@gmail.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>