AMDGPU/SI: Remove calling convention assertion from LowerFormalArguments()

Summary:
We currently ignore the calling convention, so there is no real reason to
assert on the calling convention of functions.

Reviewers: arsenm

Subscribers: arsenm, llvm-commits

Differential Revision: http://reviews.llvm.org/D13367

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249468 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed