MN10300 arch headers and place them instead in the same directories as contain
the .c files for the processor and unit implementations.

This permits the symlinks include/asm/proc and include/asm/unit to be
dispensed with.  This does, however, require that #include <asm/proc/xxx.h> be
converted to #include <proc/xxx.h> and similarly for asm/unit -> unit.

Signed-off-by: David Howells <dhowells@redhat.com>