ARM: Enable TS-78XX features in unknown revisions

When the manufacturer increases the revision number the platform
devices for the RTC, NAND, and RNG disappear. We should assume
new revisions have these devices instead of assuming they do not.

Signed-off-by: Michael Spang <mspang@csclub.uwaterloo.ca>
Signed-off-by: Nicolas Pitre <nico@fluxnic.net>