arm64: dts: imx8mp-tqma8mpql-mba8mpxl: Remove unused ocram node

This node is unused and origins from downstream kernel where it is
used for the DSP.

Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>