[amx] Test Enhance: move test src to top folder

[hongyuni]

move test source code to top folder amx to align with all other features hierarchy, for runtests.py execution alignment

[Test Components] amx
[Test Types] any
[Supported Devices] all-generic

[ysun]

I have concern moving tmul to the top folder.
1, tmul is part of AMX i think. It is too small to take it as a "feature". I prefer keep tmux in AMX folder, at least move all source code into AMX folder.
2, I'm not sure whether it would impact the external framwork like eoch or ancert AMX test execution.

[hongyuni]

I have concern moving tmul to the top folder. 1, tmul is part of AMX i think. It is too small to take it as a "feature". I prefer keep tmux in AMX folder, at least move all source code into AMX folder. 2, I'm not sure whether it would impact the external framwork like eoch or ancert AMX test execution.

1. Thanks. It makes sense to me, for future larger scope of AMX testing, keep tmul test src inside tmul sub-folder is a better option
2. if eoch or ancert AMX test execution is using runtests.py, just make sure to use command as discussed in amx tests can not be run with runtests.py #396
   $ ./runtests.py -f amx/tmul -t amx/tests