sun55iw3: add bare Allwinner A523 SBROM and MBROM dump
This is from a Teclast P85T tablet with that SoC, and the secure fuse burnt. Reading the BROM from non-secure state (via FEL) returns all zeroes, but putting some code in a TOC0 image on an SD card gets that executed in secure state. This allows copying the BROM to SRAM, then going to FEL, and read the copy from there.
SBROM is located at address 0x0, and is the primary (secure) reset entry point. Allwinner calls the second blob MBROM ("Medium Boot module"), It is located at address 0x10000, so in the gap between SBROM and SRAM.
I struggled to get the other files initialised properly, so this is just the blob.hex. If you can make this to work properly, please fix this commit up, if possible. I have quite some symbols and comments already in a separate objdump copy, so happy to contribute that later.