Kernel: Remove i686 support

Author: https://github.com/supercomputer7
Commit: 5ff318cf3a
Pull-request: https://github.com/SerenityOS/serenity/pull/15467
Issue: https://github.com/SerenityOS/serenity/issues/15444
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/Hendiadyoin1
Reviewed-by: https://github.com/fuel-pcbox

Kernel/CommandLine.cpp

@@ -149,7 +149,7 @@ UNMAP_AFTER_INIT PCIAccessLevel CommandLine::pci_access_level() const
     auto value = lookup("pci"sv).value_or("ecam"sv);
     if (value == "ecam"sv)
         return PCIAccessLevel::MemoryAddressing;
-#if ARCH(I386) || ARCH(X86_64)
+#if ARCH(X86_64)
     if (value == "io"sv)
         return PCIAccessLevel::IOAddressing;
 #endif