JitArm64: MultiplyImmediate - Handle 0

Multiplication by zero always gives zero.

Before:
0x52800019   mov    w25, #0x0
0x1b197f5b   mul    w27, w26, w25

After:
Nothing!

Source/Core/Core/PowerPC/JitArm64/JitArm64_Integer.cpp

@@ -878,7 +878,19 @@ void JitArm64::addic(UGeckoInstruction inst)
 
 bool JitArm64::MultiplyImmediate(u32 imm, int a, int d, bool rc)
 {
-  return false;
+  if (imm == 0)
+  {
+    gpr.SetImmediate(d, 0);
+    if (rc)
+      ComputeRC0(gpr.GetImm(d));
+  }
+  else
+  {
+    // Immediate did not match any known special cases.
+    return false;
+  }
+
+  return true;
 }
 
 void JitArm64::mulli(UGeckoInstruction inst)