[SIMode] Fix typo in Status constructor

As noted in https://www.viva64.com/en/b/0629/ (Snippet No. 36) and the scan-build CI reports (https://llvm.org/reports/scan-build/report-SIModeRegister.cpp-Status-1-1.html#EndPath), rL348754 introduced a typo in the Status constructor due to argument variable names shadowing the member variable names.

Differential Revision: https://reviews.llvm.org/D61595

llvm-svn: 360236