default or selected kernelversion does not have config value CONFIG_FM10K_VXLAN.
Result is shown for kernelversion 5.4.33

Virtual eXtensible Local Area Network Support

configname: CONFIG_FM10K_VXLAN

Linux Kernel Configuration
└─>Device Drivers
└─>Network device support
└─>Ethernet driver support
└─>Virtual eXtensible Local Area Network Support
In linux kernel since version 3.18 (release Date: 2014-12-07)  
This allows one to create VXLAN virtual interfaces that provide
Layer 2 Networks over Layer 3 Networks. VXLAN is often used
to tunnel virtual network infrastructure in virtualized environments.
Say Y here if you want to use Virtual eXtensible Local Area Network
(VXLAN) in the driver.