[clang] [llvm] [AVR] Add many new AVR MCU model definitions (PR #144229)

[Ben Shi via llvm-commits]

benshi001 wrote:

> @tomtor @benshi001 I just tried your latest revision on the top of tree, and both `check-llvm` and `check-clang` passed.

Thanks for your help !

https://github.com/llvm/llvm-project/pull/144229