release: arm64: Use loader.efi as bootaa64.efi for RPI3 and PINE64

boot1.efi have some trouble to read MBR partitions, it needs them to be
aligned a certain way while loader.efi can cope with them either way.
We want to switch to loader.efi as the main efi loader everywhere, it seems
that arm64 using MBR partition will be the guinea pig.

Tested On: RPI3, Pine64
Reviewed by: imp
Approved by: gjb