[AArch64] Remove a duplicate call to setHasWinCFI. NFCI.

[mstorsjo]

Summary

The function already has a cleanup scope that calls the same whenever the function is exited. When reading the code, seeing that this return codepath has an explicit call while other return paths lack it is confusing.

In the hypothetical case of a function having a prologue that set the HasWinCFI flag in the MF, but the epilogue containing no WinCFI instructions, the HasWinCFI flag in the MF would end up reset back to false.

[efriedma]

LGTM

llvm/lib/Target/AArch64/AArch64FrameLowering.cpp

if (AfterCSRPopSize) {
 
     emitFrameOffset(MBB, FirstSPPopI, DL, AArch64::SP, AArch64::SP,
                     {(int64_t)AfterCSRPopSize, MVT::i8}, TII,
                     MachineInstr::FrameDestroy, false, NeedsWinCFI, &HasWinCFI);
   }
   if (NeedsWinCFI && HasWinCFI)
     BuildMI(MBB, MBB.getFirstTerminator(), DL, TII->get(AArch64::SEH_EpilogEnd))
         .setMIFlag(MachineInstr::FrameDestroy);
-
-  MF.setHasWinCFI(HasWinCFI);
 }
 
 /// getFrameIndexReference - Provide a base+offset reference to an FI slot for
 /// debug info.  It's the same as what we use for resolving the code-gen
 /// references for now.  FIXME: This can go wrong when references are
 /// SP-relative and simple call frames aren't used.
 int AArch64FrameLowering::getFrameIndexReference(const MachineFunction &MF,
                                                  int FI,