CONFIG_ARCH_INTEL_SOCFPGA is not available for the default architecture x86.
Result is shown for architecture arm64
default or selected kernelversion does not have config value CONFIG_ARCH_INTEL_SOCFPGA.
Result is shown for kernelversion 5.13-rc1

Intel's SoCFPGA ARMv8 Families


Linux Kernel Configuration
└─> Platform selection
└─> Intel's SoCFPGA ARMv8 Families

This enables support for Intel's SoCFPGA ARMv8 families:
Stratix 10 (ex. Altera), Agilex and eASIC N5X.