[llvm] [AMDGPU] update LDS block size for gfx1250 (PR #167614)

[Changpeng Fang via llvm-commits]

changpeng wrote:

> Printing strings is cheap, this shall show a diff in the KD dump
Are we supposed not to see any diff in KD dump/printing when we just change the LDS block size  (for amdhsa)? 
In the docs, GRANULATED_LDS_SIZE "must be 0", and CP is responsible to compute and set it when the dynamically allocated LDS is available?
Is my understanding correct?

https://github.com/llvm/llvm-project/pull/167614