efi_loader: reenable selftest

ad503ffe9c6 efi_loader: refactor boot device and loaded_image handling
leads to an error when building with CONFIG_CMD_BOOTEFI_SELFTEST=y
This patch fixes the problem.

Fixes: ad503ffe9c6 efi_loader: refactor boot device and loaded_image handling
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>