Revert r352985 "[X86] Print %st(0) as %st to match what gcc inline asm uses as the...

Revert r352985 "[X86] Print %st(0) as %st to match what gcc inline asm uses as the clobber name to make MS inline asm work correctly"

Looking into gcc and objdump behavior more this was overly aggressive. If the register is encoded in the instruction we should print %st(0), if its implicit we should print %st.

I'll be making a more directed change in a future patch.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@353013 91177308-0d34-0410-b5e6-96231b3b80d8