[mips][msa] Correct sld and sldi builtins.

Summary: The result register of these instructions is also the first operand.

Reviewers: jacksprat, dsanders

Reviewed By: dsanders

Differential Revision: http://llvm-reviews.chandlerc.com/D2362
Differential Revision: http://llvm-reviews.chandlerc.com/D2363



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196910 91177308-0d34-0410-b5e6-96231b3b80d8