conf/machine: move tune files to architecture directories

Move all of the tune files found in conf/machine/include into their
respective architecture directories in that same location.  All
references to these will need to be updated.  So, change the relevant
ones for this tree in this commit as well.

For the ARM tunes, nest them one further into armv8a, armv8m, etc. and
rename some to make them uniform with the rest of the tunes.

Signed-off-by: Jon Mason <jdmason@kudzu.us>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>