arm64: dts: ti: Add support for AM6254atl SiP SK

arm64: dts: ti: Add support for AM6254atl SiP SK

This patch adds the dt for SK-AM62-SIP, which uses the existing
SK-AM62 board design with the new AM6254atl SiP. This changes the
location of memory node from the board dts to SoC level dtsi
(k3-am6254atl in our case).

Therefore this patch introduces the new 'k3-am625-sk-common.dtsi'
which represents the common hardware used for both 'am625-sk' and
'am6254atl-sk' boards with the inheritance hierarchy modified to:

k3-am625-sk.dts:

     k3-am62    k3-am62x-sk-common
        |            |
    k3-am625    k3-am625-sk-common
        |            |
        +-----+------+
              |
         k3-am625-sk

k3-am6254atl-sk.dts:

     k3-am62
        |
     k3-am625       k3-am62x-sk-common
        |                |
    k3-am6254atl    k3-am625-sk-common
        |                |
        +-------+--------+
                |
         k3-am6254atl-sk

Signed-off-by: Anshul Dalal <anshuld@ti.com>
Reviewed-by: Bryan Brattlof <bb@ti.com>
Link: https://patch.msgid.link/20250814134531.2743874-5-anshuld@ti.com
Signed-off-by: Nishanth Menon <nm@ti.com>
[ upstream commit: 2517e476b819df986fa1fe53927c099032bb72dc ]

(cherry picked from commit 58cd89aff167661dbae0c9911282ea3f1b8212cc)