Documentation: remove 'mach' from dontdiff file

The mach entry in the dontdiff file causes all the
arch/arm/mach-*/include/mach directories to be skipped.
Signed-off-by: NH Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Documentation/dontdiff

@@ -158,7 +158,6 @@ logo_*.c
 logo_*_clut224.c
 logo_*_mono.c
 lxdialog
-mach
 mach-types
 mach-types.h
 machtypes.h