JitArm64: MultiplyImmediate - Handle 2^n + 1

By taking advantage of ARM64's ability to shift an input register by any
amount, we can calculate multiplication by a number that is one more
than a power of two with a single instruction.

Before:
0x52800838   mov    w24, #0x41
0x1b187f7b   mul    w27, w27, w24

After:
0x0b1b1b7b   add    w27, w27, w27, lsl #6

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

@@ -904,6 +904,15 @@ bool JitArm64::MultiplyImmediate(u32 imm, int a, int d, bool rc)
     if (rc)
       ComputeRC0(gpr.R(d));
   }
+  else if (MathUtil::IsPow2(imm - 1))
+  {
+    const int shift = IntLog2(imm - 1);
+
+    gpr.BindToRegister(d, d == a);
+    ADD(gpr.R(d), gpr.R(a), gpr.R(a), ArithOption(gpr.R(a), ShiftType::LSL, shift));
+    if (rc)
+      ComputeRC0(gpr.R(d));
+  }
   else
   {
     // Immediate did not match any known special cases.