move Linux kernel to the subdirectory linux
move Linux kernel to the subdirectory linux

stlankes/HermitCore,stlankes/HermitCore,RWTH-OS/HermitCore,RWTH-OS/HermitCore,RWTH-OS/HermitCore,stlankes/HermitCore,stlankes/HermitCore,RWTH-OS/HermitCore,stlankes/HermitCore,RWTH-OS/HermitCore,stlankes/HermitCore,RWTH-OS/HermitCore