[mlir][Linalg] Fix Linalg EDSC builders

Summary:
This diff fixes the fact that the method `mlir::edsc::makeGenericLinalgOp`
incorrectly adds 2 blocks to Linalg ops.

Tests are updated accordingly.

Reviewers: ftynse, hanchung, herhut, pifon2a, asaadaldien

Reviewed By: asaadaldien

Subscribers: merge_guards_bot, mehdi_amini, rriddle, jpienaar, burmako, shauheen, antiagainst, arpith-jacob, mgester, lucyrfox, liufengdb, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D72780