d/p/imx8: Fix missing ATF file in binman image generation
Task: https://phabricator.apertis.org/T8567
During the last rebase on imx8mn-bsh-smm2 patches, the atf-bl31 path got broken. Fix this.
Task: https://phabricator.apertis.org/T8567
During the last rebase on imx8mn-bsh-smm2 patches, the atf-bl31 path got broken. Fix this.