refactor build script and workflow

[gtxaspec]

produce *nor, *nand named binaries
expand build.sh in repo and workflow

[gtxaspec]

f5c6dc5
no nand yet

[gtxaspec]

Add mmc builds to build.sh and workflow

[gtxaspec]

added mmc0 e55643e

[gtxaspec]

only nand builds are missing at the moment