dt-bindings: display: ti,k2g-dss: Remove ports-node from example

The ports node was removed from the binding during the review round,
but it still remained in the example-node.

Fixes: bae8f085 ("dt-bindings: display: ti,k2g-dss: Add dt-schema yaml binding")
Signed-off-by: Jyri Sarha <jsarha@ti.com>