CONFIG_PPC_SCOM is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

CONFIG_PPC_SCOM (not configurable)

modulename: scom.ko

and/or

opal-xscom.ko

configname: CONFIG_PPC_SCOM

Linux Kernel Configuration
└─>PPC_SCOM
In linux kernel since version 3 (release Date: 2011-07-21)  
source code:
arch/powerpc/sysdev/scom.c
is depended by
CONFIG_PPC_POWERNV