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

Altera SOCFPGA family

configname: CONFIG_ARCH_SOCFPGA

Linux Kernel Configuration
└─>Altera SOCFPGA family
In linux kernel since version 3.1 (release Date: 2011-10-24)  


is selected by
CONFIG_MFD_ALTERA_SYSMGR