[NVPTX] Fix PR41651

Summary:
- Use the passed `DL` directly as retrieving data layout from CS by
  checking the called function is not reliable. Under indirect function
  call, there is no called function.

Subscribers: jholewinski, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D65468

llvm-svn: 367349