Implemented more arm64 instructions

src/arm/Return.go

@@ -1,6 +1,6 @@
 package arm
 
 // Return transfers program control to the caller.
-func Return(code []byte) []byte {
-	return append(code, 0xC0, 0x03, 0x5F, 0xD6)
+func Return() uint32 {
+	return 0xD65F03C0
 }