[turbofan] Float32 LinkageLocations need double registers too.

R=bmeurer@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1268433003

Cr-Commit-Position: refs/heads/master@{#29955}

src/compiler/instruction-selector-impl.h

@@ -224,7 +224,8 @@ class OperandGenerator {
                                 location.AsCalleeFrameSlot(), virtual_register);
     }
     // a fixed register.
-    if (RepresentationOf(type) == kRepFloat64) {
+    MachineType rep = RepresentationOf(type);
+    if (rep == kRepFloat64 || rep == kRepFloat32) {
       return UnallocatedOperand(UnallocatedOperand::FIXED_DOUBLE_REGISTER,
                                 location.AsRegister(), virtual_register);
     }