[mips] Fix unused variable warning for release builds introduced by r268379.

llvm-svn: 268383
diff --git a/llvm/lib/Target/Mips/InstPrinter/MipsInstPrinter.cpp b/llvm/lib/Target/Mips/InstPrinter/MipsInstPrinter.cpp
index ff91cc0..eae5ebe 100644
--- a/llvm/lib/Target/Mips/InstPrinter/MipsInstPrinter.cpp
+++ b/llvm/lib/Target/Mips/InstPrinter/MipsInstPrinter.cpp
@@ -138,9 +138,7 @@
   } else
     SRE = cast<MCSymbolRefExpr>(Expr);
 
-  MCSymbolRefExpr::VariantKind Kind = SRE->getKind();
-
-  assert(Kind == MCSymbolRefExpr::VK_None && "Invalid kind!");
+  assert(SRE->getKind() == MCSymbolRefExpr::VK_None && "Invalid kind!");
 
   SRE->getSymbol().print(OS, MAI);