HackStudio: Fix ds => fs typo in fs changed check in RegistersModel

The changed check for `fs` was accidentally comparing the current `ds`
to the previous `fs`.

Userland/DevTools/HackStudio/Debugger/RegistersModel.cpp

@@ -89,7 +89,7 @@ RegistersModel::RegistersModel(const PtraceRegisters& current_regs, const Ptrace
  m_registers.append({ "ss", current_regs.ss, current_regs.ss != previous_regs.ss });
  m_registers.append({ "ds", current_regs.ds, current_regs.ds != previous_regs.ds });
  m_registers.append({ "es", current_regs.es, current_regs.es != previous_regs.es });
- m_registers.append({ "fs", current_regs.fs, current_regs.ds != previous_regs.fs });
+ m_registers.append({ "fs", current_regs.fs, current_regs.fs != previous_regs.fs });
  m_registers.append({ "gs", current_regs.gs, current_regs.gs != previous_regs.gs });
 }