arm: dts: k3-j784s4-ddr: Refactor J784s4 ddr file to a common file

Refactor J784s4 ddr file to a common file which uses the
superset device to allow reuse in j742s2-evm which uses the subset part.

Signed-off-by: Manorit Chawdhry <m-chawdhry@ti.com>
3 files changed