arm: dts: k3-am68: Sync from Linux tag v6.6-rc1

The following commit syncs the device tree from Linux tag
v6.6-rc1 to U-boot and fixes the following to be compatible with
the future syncs -

- Include k3-am68-sk-base-board.dts file

    Remove the duplicated pinmuxes from r5 and -u-boot.dtsi files and
    include k3-am68-sk-base-board.dts for Linux fixes to propagate
    to U-boot.

- Fixing the mcu_timer0

    Remove timer0 and use the mcu_timer0 defined in mcu-wakeup.dtsi

- Fixing secure proxy nodes

    Linux DT now have these nodes defined so remove them and rename to
    use the Linux DT ones.

- Remove cpsw node

    The compatible is now fixed and the node is not required in
    -u-boot specifically

- Remove aliases and chosen node

    Use these from Linux and don't override when not required.

- Remove /delete-property/ from sdhci nodes

    We have the necessary clock and dev data so remove these.

- Remove dummy_clocks and fs_loader0

    These weren't being used anywhere so remove it.

- Remove mcu_ringacc override

All these have been put in a single commit to not break the
bisectability.

Reviewed-by: Neha Malcom Francis <n-francis@ti.com>
Reviewed-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Manorit Chawdhry <m-chawdhry@ti.com>