linux-phytec-fsl

dts: imx7s-pcm-061-0502100e: smaller cma memory region required for 256MB DDR

imx7d.dtsi specifies cma region size 0x14000000, however this is too large
and no cma is allocated as a result.

Signed-off-by: Anna Horstmann <ahorstmann@phytec.com>