CONFIG_ARM is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_ARM (not configurable)

modulename: setup-bus.ko

configname: CONFIG_ARM

Linux Kernel Configuration
└─>ARM
In linux kernel since version 2.6.12  
The ARM series is a line of low-power-consumption RISC chip designs
licensed by ARM Ltd and targeted at embedded applications and
handhelds such as the Compaq IPAQ. ARM-based PCs are no longer
manufactured, but legacy ARM-based PC hardware remains popular in
Europe. There is an ARM Linux project with a web page at
<http://www.arm.linux.org.uk/>.

source code:
drivers/pci/
selects
CONFIG_ARCH_BINFMT_ELF_RANDOMIZE_PIE
CONFIG_ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
CONFIG_ARCH_HAS_TICK_BROADCAST
CONFIG_ARCH_HAVE_CUSTOM_GPIO_H
CONFIG_ARCH_SUPPORTS_ATOMIC_RMW
CONFIG_ARCH_WANT_IPC_PARSE_VERSION
CONFIG_BUILDTIME_EXTABLE_SORT
CONFIG_CLONE_BACKWARDS
CONFIG_CPU_PM
CONFIG_DCACHE_WORD_ACCESS
CONFIG_GENERIC_ATOMIC64
CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
CONFIG_GENERIC_IDLE_POLL_SETUP
CONFIG_GENERIC_IRQ_PROBE
CONFIG_GENERIC_IRQ_SHOW
CONFIG_GENERIC_PCI_IOMAP
CONFIG_GENERIC_SCHED_CLOCK
CONFIG_GENERIC_SMP_IDLE_THREAD
CONFIG_GENERIC_STRNCPY_FROM_USER
CONFIG_GENERIC_STRNLEN_USER
CONFIG_HARDIRQS_SW_RESEND
CONFIG_HAVE_ARCH_JUMP_LABEL
CONFIG_HAVE_ARCH_KGDB
CONFIG_HAVE_ARCH_SECCOMP_FILTER
CONFIG_HAVE_ARCH_TRACEHOOK
CONFIG_HAVE_BPF_JIT
CONFIG_HAVE_CONTEXT_TRACKING
CONFIG_HAVE_C_RECORDMCOUNT
CONFIG_HAVE_DEBUG_KMEMLEAK
CONFIG_HAVE_DMA_API_DEBUG
CONFIG_HAVE_DMA_ATTRS
CONFIG_HAVE_DMA_CONTIGUOUS
CONFIG_HAVE_DYNAMIC_FTRACE
CONFIG_HAVE_FTRACE_MCOUNT_RECORD
CONFIG_HAVE_FUNCTION_GRAPH_TRACER
CONFIG_HAVE_FUNCTION_TRACER
CONFIG_HAVE_GENERIC_DMA_COHERENT
CONFIG_HAVE_HW_BREAKPOINT
CONFIG_HAVE_IDE
CONFIG_HAVE_IRQ_TIME_ACCOUNTING
CONFIG_HAVE_KERNEL_GZIP
CONFIG_HAVE_KERNEL_LZ4
CONFIG_HAVE_KERNEL_LZMA
CONFIG_HAVE_KERNEL_LZO
CONFIG_HAVE_KERNEL_XZ
CONFIG_HAVE_KPROBES
CONFIG_HAVE_KRETPROBES
CONFIG_HAVE_MEMBLOCK
CONFIG_HAVE_MOD_ARCH_SPECIFIC
CONFIG_HAVE_OPROFILE
CONFIG_HAVE_PERF_EVENTS
CONFIG_HAVE_REGS_AND_STACK_ACCESS_API
CONFIG_HAVE_SYSCALL_TRACEPOINTS
CONFIG_HAVE_UID16
CONFIG_IRQ_FORCED_THREADING
CONFIG_KTIME_SCALAR
CONFIG_MODULES_USE_ELF_REL
CONFIG_OLD_SIGACTION
CONFIG_OLD_SIGSUSPEND3
CONFIG_PERF_USE_VMALLOC
CONFIG_RTC_LIB
CONFIG_SYS_SUPPORTS_APM_EMULATION