[X86][SSE] Update register class during MOVSD/MOVSS - BLENDPD/BLENDPS commutation

MOVSD/MOVSS take a 128-bit register and a FR32/FR64 register input, the commutation code wasn't taking this into account leading to verification errors.

This patch inserts a vreg copy mi to ensure that the registers are correct.

Fix for PR30607

Differential Revision: https://reviews.llvm.org/D25280

llvm-svn: 283539