boss: Return buff_size in parameter 2 of ReceiveProperty.

src/core/hle/service/boss/boss.cpp

@@ -404,7 +404,7 @@ void ReceiveProperty(Service::Interface* self) {
 
     cmd_buff[0] = IPC::MakeHeader(0x16, 0x2, 0x2);
     cmd_buff[1] = RESULT_SUCCESS.raw;
-    cmd_buff[2] = 0; // stub 0 (32 bit value)
+    cmd_buff[2] = buff_size; // Should be actual number of read bytes.
     cmd_buff[3] = (buff_size << 4 | 0xC);
     cmd_buff[4] = buff_addr;