x86: Cleanup apic/ioapic/x2apic setup code

While reviewing Jiangs interrupt remapping patch set, I had several serious WTF moments when trying to understand what that code is doing.

The main issues I've seen are:

- Blindly copy and pasted code

- Random places which initialize bits and pieces

- Code which got mindlessly expanded with duct tape and glue without considering readability and maintainability.

- Missing inline stubs which result in a ifdef nightmare

- Superflous inline stubs to artificially avoid sensible ifdefs

The deeper I looked the more I started to get grumpy about that maze and finally sat down and cleaned it up seriously. One bug I fixed on the way (surprise, surprise) got folded into Jiangs series which is now in tip/x86/apic. The other one is not that crucial and cant be fixed in the previous code without adding more mess.

The following patch series applies on top of tip/x86/apic. It cleans up and consolidates the apic/ioapic/x2apic setup functions.

Please give it a proper review and testing.

Thanks,

tglx

---
 arch/x86/include/asm/smpboot_hooks.h |   68 ------
 tip/arch/x86/include/asm/apic.h      |   57 +----
 tip/arch/x86/include/asm/io_apic.h   |    5 
 tip/arch/x86/kernel/apic/apic.c      |  395 ++++++++++++++++++-----------------
 tip/arch/x86/kernel/apic/io_apic.c   |   13 -
 tip/arch/x86/kernel/cpu/common.c     |    2 
 tip/arch/x86/kernel/smpboot.c        |  113 +++++-----
 tip/init/main.c                      |   14 -
 8 files changed, 308 insertions(+), 359 deletions(-)