dontdiff: Fix asm exclude

Now that the headers are in arch/foo/include/asm we don't want to exclude
them when preparing diff files.

Closes-bug: 12921
Signed-off-by: NAlan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Documentation/dontdiff

@@ -62,7 +62,6 @@ aic7*reg_print.c*
 aic7*seq.h*
 aicasm
 aicdb.h*
-asm
 asm-offsets.h
 asm_offsets.h
 autoconf.h*