don't diff generated firmware files

With the new firmware infrastructure in 2.6.27, some files are generated and shouldn't be
diffed; add these 2 to the "dontdiff" file
Signed-off-by: NArjan van de Ven <arjan@Linux.intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Documentation/dontdiff

@@ -5,6 +5,8 @@
 *.css
 *.dvi
 *.eps
+*.fw.gen.S
+*.fw
 *.gif
 *.grep
 *.grp