linux-phytec-fsl

IMX7FLY-90 dts: imx7s-phyboard-zeta-002: add dts for running FreeRTOS on M4

Configure RPMsg and disable peripherals used by FreeRTOS demos.
Configured for 256MB DDR.

Signed-off-by: Anna Horstmann <ahorstmann@phytec.com>
(cherry picked from commit 85e60bfb5bfd44c50706c6a8453dba9ca310b81a)