Add makefile for "afutests": afp and mcp

[luyong6]

Is the folder "afutests" for a sanity check? If so, please add Makefile for that.

[luyong6]

And the Readme of AFP usage is not in a good shape.
@deece I don't know if I should write to you but please convey it to the right person. Thank you!

[deece]

The afutests dir contains exercisers for some of the reference AFU images, they are included in LibOCXL so that they can be versioned alongside the library and used as an example if needed (although they are much more verbose than desired as sample code).

They are automatically built by the top level Makefile.

@luyong Do you have specific things that can be improved in the AFP documentation?

@philippe56 Anything to add?

[luyong6]

Oh I just found that the output binary executables were put in folder "afuobj"
Would you add one line in README? That's simple but friendly.

And the help message of AFP currently is crowded as below and no one would read.
I suggest just to say "please run ./ocxl_afp3 -h" to get the options before running it.

Usage: ocxl_afp3 [ options ] --tags_ld Number of tags for loads. Default=0 --tags_st Number of tags for stores. Default=0 0 - 0 tags (disabled) 1 - 1 tag 2 - 2 tags 3 - 4 tags 4 - 16 tags 5 - 64 tags 6 - 256 tags 7 - 512 tags --size_ld Data size, in Bytes, for loads. Supported values: 64, 128, 256. Default=128 --size_st Data size, in Bytes, for stores. Supported values: 64, 128, 256. Default=128 --npu_ld Use rd_wnitc.n for loads. Default is rd_wnitc --npu_st Use dma_w.n for stores. Default is dma_w --num Number of times to check perf counts. Default is 3 --wait Amount of seconds to wait between perf count reads. Default is 2 --prefetch Initialize buffer memory --offsetmask Determines how much of buffer to use. Default 512kB. Valid Range: 4K-512M. Format: NumberLetter, e.g. 4K, 512K, 1M, 512M --timeout Default=1 seconds --verbose Verbose output --help Print this message