microblaze: clinkage.h

Nothing includes <asm/clinkage.h>. It has actually never been included
since it was added to the tree in commit
9981cd94 ("microblaze_v8: clinkage.h
linkage.h sections.h kmap_types.h"). That's not surprising, since
including it is indistinguishable from including <linux/linkage.h>. It
can safely be removed.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>