arm: dts: fsl-ls1088a: move u-boot bootph tags into u-boot only files

arm: dts: fsl-ls1088a: move u-boot bootph tags into u-boot only files

This moves the bootph-all tags that were added in commit a593c1fec579
("arch: arm: dts: fsl-ls1088a.dtsi: tag serial nodes with bootph-all")
into a u-boot only include.

Due to the way the U-Boot device tree "tweak" system is setup[1],
we need to have a per-board <boardname>-u-boot.dtsi, which will
include the "fsl-ls1088a-u-boot.dtsi" tweaks.

By doing so, future updates to fsl-ls1088a.dtsi from upstream
(Linux kernel) can just be copied directly into the U-Boot tree,
without worrying about any extra data local to U-Boot.

Signed-off-by: Mathew McBride <matt@traverse.com.au>
[1] - https://u-boot.readthedocs.io/en/latest/develop/devicetree/control.html#adding-tweaks-for-u-boot
The CONFIG_SYS_SOC, CONFIG_SYS_CPU and CONFIG_SYS_VENDOR
values are the same for the entire Layerscape family,
meaning there is no ability to create a LS1088A only
file here. But we will be adding per-board tweaks
later in any case.
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Tested-by: Ioana Ciornei <ioana.ciornei@nxp.com> # on LS1088A-RDB