[X86][SSE] Fix load folding for (V)CVTDQ2PD

This only requires a 64-bit memory source, not the whole 128-bits. But the 128-bit case is still supported via X86InstrInfo::foldMemoryOperandImpl

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297523 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed