AMDGPU: Move INDIRECT_BASE_ADDR definition out of common files

Summary: This is only used by R600.

Reviewers: arsenm

Reviewed By: arsenm

Subscribers: kzhuravl, wdng, nhaehnle, yaxunl, dstuttard, tpr, llvm-commits, t-tye

Differential Revision: https://reviews.llvm.org/D35926

llvm-svn: 309476