CONFIG_INFINIBAND_EFA is not available for thedefaultarchitecture x86.
Result is shown for architecture 64BIT

Amazon Elastic Fabric Adapter (EFA) support

modulename: efa.ko

configname: CONFIG_INFINIBAND_EFA

Linux Kernel Configuration
└─>Device Drivers
└─>InfiniBand support
└─>Amazon Elastic Fabric Adapter (EFA) support
In linux kernel since version 5.1 (release Date: 2019-05-05)  
This driver supports Amazon Elastic Fabric Adapter (EFA).

To compile this driver as a module, choose M here.
The module will be called efa.

source code: