[arm] Drop SMMLS support.

src/base/bits.cc

Index: src/base/bits.cc
diff --git a/src/base/bits.cc b/src/base/bits.cc
index 7a3fb6d33159dfd64c88fb16683aabf2248f05a8..2818b939aa94bb1c43761ef7add1386b0050c214 100644
--- a/src/base/bits.cc
+++ b/src/base/bits.cc
@@ -32,13 +32,6 @@ int32_t SignedMulHighAndAdd32(int32_t lhs, int32_t rhs, int32_t acc) {
                            bit_cast<uint32_t>(SignedMulHigh32(lhs, rhs)));
 }
 
-
-int32_t SignedMulHighAndSub32(int32_t lhs, int32_t rhs, int32_t acc) {
-  return bit_cast<int32_t>(bit_cast<uint32_t>(acc) -
-                           bit_cast<uint32_t>(SignedMulHigh32(lhs, rhs)));
-}
-
-
 }  // namespace bits
 }  // namespace base
 }  // namespace v8