Rename VBROADCASTSDrm into VBROADCASTSDYrm to match the naming convention.

Allow the folding of vbroadcastRR to vbroadcastRM, where the memory operand is a spill slot.

PR12782.

Together with Michael Kuperstein <michael.m.kuperstein@intel.com>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160230 91177308-0d34-0410-b5e6-96231b3b80d8