[mlir][gpu] Refactor functions for workgroup and private buffer attributions.
Summary:
Consolidate interfaces adding workgroup and private buffer attributions in GPU
dialect.
Note all private buffer attributions must follow workgroup buffer attributions.
Reviewers: herhut
Subscribers: mehdi_amini, rriddle, jpienaar, shauheen, antiagainst, nicolasvasilache, csigg, arpith-jacob, mgester, lucyrfox, liufengdb, stephenneuendorffer, Joonsoo, grosul1, frgossen, Kayjukh, llvm-commits
Tags: #llvm, #mlir
Differential Revision: https://reviews.llvm.org/D79508