efi_loader: correct uboot_bin_env.its file format

Up to now the EFI capsule Python tests were always skipped. The reason is
that mkimage fails with:

uboot_bin_env.its:13.21-23.5: Warning (unit_address_vs_reg):
/images/u-boot-bin@100000: node has a unit name, but no reg property
uboot_bin_env.its:24.21-34.5: Warning (unit_address_vs_reg):
/images/u-boot-env@150000: node has a unit name, but no reg property

If a unit in a device-tree has an address, a reg property must be provided.
But adding a reg property is not the solution here.

Since 2017 unit addresses are disallowed for FIT,
cf. common/image-fit.c:1624.

So remove the unit addresses in uboot_bin_env.its.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>