x86: section mismatch fixes, #2

This patch fixes section mismatch warnings in smpboot_setup_io_apic().

WARNING: arch/x86/kernel/built-in.o(.text+0x11781): Section mismatch in reference from the function smpboot_setup_io_apic()
to the function .init.text:setup_IO_APIC()
The function smpboot_setup_io_apic() references
the function __init setup_IO_APIC().
This is often because smpboot_setup_io_apic lacks a __init
annotation or the annotation of setup_IO_APIC is wrong.

Signed-off-by: Jacek Luczak <luczak.jacek@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>