ARM: dts: AM33XX: Add EDMA support

Adds AM33XX EDMA support to the am33xx.dtsi as documented in
Documentation/devicetree/bindings/dma/ti-edma.txt

[Joel Fernandes <joelf@ti.com>]
Drop DT entries that are non-hardware-description as discussed in [1]

[1] https://patchwork.kernel.org/patch/2226761/



Signed-off-by: Matt Porter <mporter@ti.com>
Signed-off-by: Joel A Fernandes <joelagnel@ti.com>
Signed-off-by: Benoit Cousson <bcousson@baylibre.com>