[amdgpu][lds] Fix missing markUsedByKernel calls and undef lookup table elements

More robust association between the kernels and lds struct.

Use poison instead of value() for lookup table elements introduced by dynamic lds lowering.

Extracted from D154946, new test from there verbatim. Segv fixed.

Fixes issues/63338

Fixes SWDEV-404491

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D154972