[X86] Teach lower1BitShuffle to match KSHIFTR that doesn't use Zeroable and only...

[X86] Teach lower1BitShuffle to match KSHIFTR that doesn't use Zeroable and only relies on undef.

This allows us to widen the type when the KSHIFTR instruction
doesn't exist for the type. If we need to shift in zeroes into
the upper elements we would need more work to guarantee zeroes
when widening.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@369227 91177308-0d34-0410-b5e6-96231b3b80d8