[mips] Partially revert r193641. Stack alignment should not be determined by
the floating point register mode.
 

llvm-svn: 194423
diff --git a/llvm/lib/Target/Mips/MipsSubtarget.h b/llvm/lib/Target/Mips/MipsSubtarget.h
index 7c17553..6b2ab12 100644
--- a/llvm/lib/Target/Mips/MipsSubtarget.h
+++ b/llvm/lib/Target/Mips/MipsSubtarget.h
@@ -217,7 +217,7 @@
 //
 static bool useConstantIslands();
 
-  unsigned stackAlignment() const { return isFP64bit() ? 16 : 8; }
+  unsigned stackAlignment() const { return hasMips64() ? 16 : 8; }
 
   // Grab MipsRegInfo object
   const MipsReginfo &getMReginfo() const { return MRI; }