u-boot-seco-imx: bump to 2021.04
First step to add OP-TEE support for SBC-C61
As of 8 April 2024, the git.seco.com instance was upgraded to the Premium version. External users and SECO customers who need access to private groups or repositories can make a request by contacting SECO support team via the ticketing platform (https://support.seco.com/).
First step to add OP-TEE support for SBC-C61