[AVR] Do not emit instructions invalid for attiny10

[AVR] Do not emit instructions invalid for attiny10

The attiny4/attiny5/attiny9/attiny10 have a slightly modified
instruction set that drops a number of useful instructions. This patch
makes sure to not emit them on these "reduced tiny" cores.

The affected instructions are:

  * lds and sts (load/store directly from data)
  * ldd and std (load/store with displacement)
  * adiw and sbiw (add/sub register pairs)
  * various other instructions that were emitted without checking
    whether the chip actually supports them (movw, adiw, etc)

There is a variant on lds and sts on these chips, but it can only
address a limited portion of the address space and is mainly useful to
load/store I/O registers (as an extension to the in and out
instructions). I have not implemented it here, implementing it can be
done in a separate patch.

This patch is not optimal. I'm sure it can be improved a lot. For
example, we could teach the instruction selector to not select lddw/stdw
instructions so that the weird pointer adjustments are not necessary.
But for now I've focused just on correctness, not on code quality.

Updates: https://github.com/llvm/llvm-project/issues/53459

Differential Revision: https://reviews.llvm.org/D131867