dmaengine: pl08x: Add Faraday FTDMAC020 to compatible list

This augments the PL08x bindings to include the Faraday Technology
FTDMAC020 DMA engine, as it is clearly a derivative of the PL08x
PrimeCell. Also specify that it needs the special peripheral ID
specified to work properly.

Cc: devicetree@vger.kernel.org
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>