ARM: dts: dra7: add entry for bb2d module

BB2D is a Vivante GC 2D Accelerator.
This adds the node to the dts file within a target module node.
Crossbar index number is used for interrupt mapping.

Signed-off-by: Gowtham Tammana <g-tammana@ti.com>
Signed-off-by: Jyri Sarha <jsarha@ti.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>