[PATCH] ARM: 2840/1: Add mach-types to Documentation/dontdiff

Patch from Michael Burian

This file is maintained by RMK's machine registry, it should not be patched.

Signed-off-by: Michael Burian <dynmail1@gassner-waagen.at>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>