ARM: OMAP4: hwmod data: add des

This fixes the following error during kernel boot:

platform 480a5000.des: Cannot lookup hwmod 'des'

Unfortunately the DES module is only documented partly
in the OMAP4430 TRM. I found an old patch from Joel,
which I took over and updated for currently mainline.

Signed-off-by: Joel Fernandes <joelf@ti.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Acked-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>