MIPS64: Fix compilation failure on target MIPS64 because of invalid

type conversion

Bug: 
Change-Id: I3e2ea55b47044bb43fe60d8287bb28df8f7d2c08
Reviewed-on: https://chromium-review.googlesource.com/608135Reviewed-by: Ivica Bogosavljevic <ivica.bogosavljevic@imgtec.com>
Reviewed-by: Miran Karić <Miran.Karic@imgtec.com>
Commit-Queue: Ivica Bogosavljevic <ivica.bogosavljevic@imgtec.com>
Cr-Commit-Position: refs/heads/master@{#47250}

test/cctest/test-assembler-mips64.cc

@@ -8468,7 +8468,7 @@ void run_msa_mi10(InstFunc GenerateVectorInstructionFunc) {
 #ifdef OBJECT_PRINT
   code->Print(std::cout);
 #endif
-  F4 f = FUNCTION_CAST<F4>(code->entry());
+  F5 f = FUNCTION_CAST<F5>(code->entry());
 
   (CALL_GENERATED_CODE(isolate, f, in_array_middle, out_array_middle, 0, 0, 0));