IR: TS-7680: Add support

[ts-kris]

With 5.10 and 6.6 support added for the TS-7680, getting Image Replicator support should follow pretty easily.

[ts-kris]

Adding the TS-7680 devicetree to the defconfig allows the unit to boot without issue.

However there are two major hurdles that need to be looked at a bit closer.

• U-Boot update support. Right now, the bootloader pokes the register in the FPGA to switch from SPI to UART, thereby disconnecting the SPI flash from the system. This would need to be undone, and MTD device support added. However, once that is done, then the existing write_uboot function should be able to work just fine in writing the bootloader. The blast.sh script can simply check /prod/device-tree/model to match TS-7680 and act on that.
• The partition layout. In order to match disk layouts of other i.MX28 based platforms (TS-7400-V2, TS-7670, TS-7600, TS-4600) the TS-7680 has a dead partition 1 (where the bootloader is on the other platforms). This essentially locks the TS-7680 in to a disk image only mode which takes a lot more time to both capture and write. It may be possible to modify the write or capture functions to handle this. But that is a longer task.