Revert "Workaround u-boot configuration for RPi4" and adapt

This reverts commit 85295ff2 and adapts to the new U-boot version in LAVA 2024.01+dfsg-1+apertis7bv2025dev3b1 which uses bootflow.

lava/devices.yaml

@@ -40,7 +40,7 @@ device-arm64-bcm2711-rpi-4-b:
       board: rpi64
       boot_method: u-boot
       boot_commands:
-        - setenv pxefile_addr_r 0x00080000; setenv scriptaddr 0x00100000; setenv kernel_addr_r 0x00200000; setenv fdt_addr_r 0x09800000; setenv ramdisk_addr_r 0x09900000; printenv; if test ${bootcount} -lt ${bootlimit}; then run distro_bootcmd; else run altbootcmd; fi
+        - if test ${bootcount} -lt ${bootlimit}; then run bootcmd; else run altbootcmd; fi
       deploy_device: sd-card
       device_type: bcm2711-rpi-4-b
       firststagedtb: broadcom/bcm2711-rpi-4-b.dtb