x86/Kconfig: Make CONFIG_PCI_CNB20LE_QUIRK depend on X86_32

I was unable to find a good description of the ServerWorks CNB20LE
chipset. However, it was probably exclusively used with the Pentium III
processor (this CPU model was used in all references to it that I
found where the CPU model was provided: dmesgs in [1] and [2];
[3] page 2; [4]-[7]).

As is widely known, the Pentium III processor did not support the 64-bit
mode, support for which was introduced by Intel a couple of years later.
So it is safe to assume that no systems with the CNB20LE chipset have
amd64 and the CONFIG_PCI_CNB20LE_QUIRK may now depend on X86_32.

Additionally, I have determined that most computers with the CNB20LE
chipset did have ACPI support and this driver was inactive on them.
I have submitted a patch to remove this driver, but it was met with
resistance [8].

[1] Jim Studt, Re: Problem with ServerWorks CNB20LE and lost interrupts
    Linux Kernel Mailing List, https://lkml.org/lkml/2002/1/11/111

[2] RedHat Bug 665109 - e100 problems on old Compaq Proliant DL320
    https://bugzilla.redhat.com/show_bug.cgi?id=665109

[3] R. Hughes-Jones, S. Dallison, G. Fairey, Performance Measurements on
    Gigabit Ethernet NICs and Server Quality Motherboards,
    http://datatag.web.cern.ch/papers/pfldnet2003-rhj.doc

[4] "Hardware for Linux",
    Probe #d6b5151873 of Intel STL2-bd A28808-302 Desktop Computer (STL2)
    https://linux-hardware.org/?probe=d6b5151873

[5] "Hardware for Linux", Probe #0b5d843f10 of Compaq ProLiant DL380
    https://linux-hardware.org/?probe=0b5d843f10

[6] Ubuntu Forums, Dell Poweredge 2400 - Adaptec SCSI Bus AIC-7880
    https://ubuntuforums.org/showthread.php?t=1689552

[7] Ira W. Snyder, "BISECTED: 2.6.35 (and -git) fail to boot: APIC problems"
    https://lkml.org/lkml/2010/8/13/220

[8] Bjorn Helgaas, "Re: [PATCH] x86/pci: drop ServerWorks / Broadcom
    CNB20LE PCI host bridge driver"
    https://lore.kernel.org/lkml/20220318165535.GA840063@bhelgaas/T/



Signed-off-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
Signed-off-by: David Heideberg <david@ixit.cz>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250321-x86_x2apic-v3-6-b0cbaa6fa338@ixit.cz