am625x_evm_a53: Tweak boot command to set fdt

When using bootflow, the fallback device tree is being constructed from the soc (k3) and board (am62x) environment variables:

Retrieving file: /dtbs/6.8.1+/k3-am62x.dtb

This file doesn't exist.

The environment variables default_device_tree and default_device_tree_arch are set in the config and will result in fdtfile being set to ti/k3-am625-sk when the findfdt script is run, which isn't the case at the moment.

Calling this script results in the correct device tree being retrieved:

Retrieving file: /dtbs/6.8.1+/ti/k3-am625-sk.dtb

Many boards are calling this script as part of their boot command. The am62x currently isn't. Rectify this so that booting works correctly.

Signed-off-by: Martyn Welch martyn.welch@collabora.com