Add support for fmul node of type v4f32.

void %foo(<4 x float> * %a) {
entry:
  %tmp1 = load <4 x float> * %a;
  %tmp2 = mul <4 x float> %tmp1, %tmp1
  store <4 x float> %tmp2, <4 x float> *%a
  ret void
}

Is selected to:

_foo:
        li r2, 0
        lvx v0, r2, r3
        vxor v1, v1, v1
        vmaddfp v0, v0, v0, v1
        stvx v0, r2, r3
        blr

llvm-svn: 24701