Now that the X86 Maximal Stack Alignment Check pass has been removed (i.e.,

Now that the X86 Maximal Stack Alignment Check pass has been removed (i.e.,
r168627), we no longer need to call the freezeReservedRegs() function a second
time.  Previously, this pass was conservatively adding the FP to the set of
reserved registers, requiring the second update to the reserved registers.
rdar://12719844

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168630 91177308-0d34-0410-b5e6-96231b3b80d8