device-pine64-a64lts: use correct u-boot file
This device uses u-boot in Alpine's u-boot-pine64 package, and NOT from the u-boot in pmaports, so the freq-specific u-boot files don't exist.
Edited by Administrator
This device uses u-boot in Alpine's u-boot-pine64 package, and NOT from the u-boot in pmaports, so the freq-specific u-boot files don't exist.