[X86] SimplifyDemandedVectorEltsForTargetNode - Move SUBV_BROADCAST narrowing handling. NFCI.
[X86] SimplifyDemandedVectorEltsForTargetNode - Move SUBV_BROADCAST narrowing handling. NFCI.

Move the narrowing of SUBV_BROADCAST to where we handle all the other opcodes.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@366660 91177308-0d34-0410-b5e6-96231b3b80d8

GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm