[Pull][SRU][X/B/D linux-aws] Add EFA driver to linux-aws

[Connor Kuehl]

BugLink: https://bugs.launchpad.net/bugs/1837638

[Impact]

* The open source EFA driver belongs in the AWS kernels (https://github.com/amzn/amzn-drivers/tree/master/kernel/linux/efa)

[Test Case]

 * Boot tested into each kernel. Loaded and unloaded the module.

[Regression Potential]

 * This is a new feature constrained to a custom kernel. Most of the patches have been reviewed and applied to mainline.
   The compatibility fixup sauce patch is big, but is all preprocessor directives for conditional compilation and these
   have been maintained in the Github repo during the driver's development. Basically, the blast radius of this pull
   request should be confined only to this new module and should not impact any other area of the kernel.