Revert "[mips] Honour -mno-odd-spreg for vector splat"

This reverts commit r291556. It was a mixture of two differentials and
was missing a test.

llvm-svn: 291562
diff --git a/llvm/lib/Target/Mips/MipsSEISelLowering.cpp b/llvm/lib/Target/Mips/MipsSEISelLowering.cpp
index b98fb91..26e0f9a 100644
--- a/llvm/lib/Target/Mips/MipsSEISelLowering.cpp
+++ b/llvm/lib/Target/Mips/MipsSEISelLowering.cpp
@@ -3377,12 +3377,8 @@
   DebugLoc DL = MI.getDebugLoc();
   unsigned Wd = MI.getOperand(0).getReg();
   unsigned Fs = MI.getOperand(1).getReg();
-  unsigned Wt1 = RegInfo.createVirtualRegister(
-      Subtarget.useOddSPReg() ? &Mips::MSA128WRegClass
-                              : &Mips::MSA128WEvensRegClass);
-  unsigned Wt2 = RegInfo.createVirtualRegister(
-      Subtarget.useOddSPReg() ? &Mips::MSA128WRegClass
-                              : &Mips::MSA128WEvensRegClass);
+  unsigned Wt1 = RegInfo.createVirtualRegister(&Mips::MSA128WRegClass);
+  unsigned Wt2 = RegInfo.createVirtualRegister(&Mips::MSA128WRegClass);
 
   BuildMI(*BB, MI, DL, TII->get(Mips::IMPLICIT_DEF), Wt1);
   BuildMI(*BB, MI, DL, TII->get(Mips::INSERT_SUBREG), Wt2)