ARM: dts: imx6qdl: Remove OCRAM clock from VPU node

According to Documentation/devicetree/bindings/media/coda.txt:

- clock-names : Should be "ahb", "per"

The OCRAM clock is already provided inside the ocram node, so remove the OCRAM
clock from the VPU node.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>