[i.MX][ENVIRONMENT] Fix some environment's variables with newest define
This fix solves this error: kernel_loadaddr=ENV_KERNEL_LOADADDR ramfs_file=ENV_RAMFS_FILENAME
With this variables not wheel set with there default (corret) value is not possible to perform the boot without using seco_config command. With this fix now is possible to directly boot the system with default (embedded into u-boot) environment set.