[turbofan] Add CalleeSavedFPRegisters to CallDescriptor.

src/compiler/mips/linkage-mips.cc

Index: src/compiler/mips/linkage-mips.cc
diff --git a/src/compiler/mips/linkage-mips.cc b/src/compiler/mips/linkage-mips.cc
index 3378213af3237f5fd9651c60ba9afd4667e4da2e..7b03340a0aa0913fa5489cd65d3c254cc65429d3 100644
--- a/src/compiler/mips/linkage-mips.cc
+++ b/src/compiler/mips/linkage-mips.cc
@@ -23,6 +23,10 @@ struct MipsLinkageHelperTraits {
     return s0.bit() | s1.bit() | s2.bit() | s3.bit() | s4.bit() | s5.bit() |
            s6.bit() | s7.bit();
   }
+  static RegList CCalleeSaveFPRegisters() {
+    return f20.bit() | f22.bit() | f24.bit() | f26.bit() | f28.bit() |
+           f30.bit();
+  }
   static Register CRegisterParameter(int i) {
     static Register register_parameters[] = {a0, a1, a2, a3};
     return register_parameters[i];