arm, davinci: add workaround for not resetting DMA bus and VPSS modules

The Buffer Logic of VPSS is Not Reset by System Reset Pin, see
http://www.ti.com/lit/er/sprz316b/sprz316b.pdf

 chapter Advisory 1.2.1
on page 9. Add workaroundcode proposed in the errata.

Signed-off-by: Heiko Schocher <hs@denx.de>
Cc: Sandeep Paulraj <s-paulraj@ti.com>
Cc: Tom Rini <tom.rini@gmail.com>