[X86] Don't prevent load folding for cvtsi2ss/cvtsi2sd based on hasPartialRegUpdate.

[X86] Don't prevent load folding for cvtsi2ss/cvtsi2sd based on hasPartialRegUpdate.

Preventing the load fold won't fix the partial register update since the
input we can fold is a GPR. So it will do nothing to prevent a false dependency
on an XMM register.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@354193 91177308-0d34-0410-b5e6-96231b3b80d8