arm: dts: k3-am65-iot2050: Fix boot

Since commit [1] A53 u-boot proper is broken. This is because nodes
marked as 'bootph-pre-ram' are not available at u-boot proper before
relocation.

To fix this we mark all nodes in u-boot.dtsi as 'bootph-all'.

[1] 9e644284 ("dm: core: Report bootph-pre-ram/sram node as pre-reloc after relocation")

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Roger Quadros <rogerq@kernel.org>
Reviewed-by: Nishanth Menon <nm@ti.com>