[llvm] [AMDGPU] Update base addr of dyn alloca considering GrowingUp stack (PR #119822)

[Christudasan Devadasan via llvm-commits]

cdevadas wrote:

> > If that's the case why do we need this while selecting the opcode https://github.com/llvm/llvm-project/pull/119822/files#diff-e78d2fbd64648d787707fd3d4e7e5b5d2f00fb9c09972937718a11237933c597R4042
> 
> To make things more complicated than necessary. This should just assert

@easyonaadit fix it in a separate patch.

https://github.com/llvm/llvm-project/pull/119822