Changed project structure to prevent code dupilcates

I just pushed lots of changes. I also changed https://github.com/QuickJack/Logi-kernel/tree/master/beaglebone-black/logibone_ra2. logibone_ra2_dm.c and logibone_ra2_dma.c were replaced by the new concept. However, there are 2 files which are not part of the Makefile: logibone_fifo_int_ra2.c and logibone_ra2.c. These files were not changed at all. I think it’s confusing to add more and more files to a folder which are not part of the projects contained in this folder. But maybe we can extend the Makefile to build other variants of the module, too. Files that are no longer required should be deleted.

Please take a look at the changes and merge.