arm64: dts: ti: Refractor AM625 SK dts

To prepare for upcoming derivative boards based on the AM625 SK,
refactor the dts file for this board into a common dtsi file that the
derivative boards will inherit and retain only those parts that are
different in the current dts file.

Signed-off-by: Anand Gadiyar <gadiyar@ti.com>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://lore.kernel.org/r/20230321-am62-lp-sk-v2-2-0a56e1694804@ti.com


Signed-off-by: Nishanth Menon <nm@ti.com>