[RK3568][RK3588] fix u-boot binaries deploy dir
Deploy loader.bin and idblock.bin to $DEPLOYDIR instead of $DEPLOY_DIR_IMAGE.
The u-boot recipes for rk3568 and rk3588 wrongly deploy loader.bin and idblock.bin to $DEPLOY_DIR_IMAGE. This causes a build error when building the images using an already-populated sstate cache instead of building it from scratch.
The docs recommend deploying to $DEPLOYDIR: https://docs.yoctoproject.org/ref-manual/classes.html#deploy
The recipes for PX30 and RK3399 use $DEPLOYDIR.