Change asserts at the top of getVectorShuffle to check that LHS and RHS have the...

Change asserts at the top of getVectorShuffle to check that LHS and RHS have the same type as the result.

Previously the asserts were only checking that RHS and LHS were the same type and had the same element type as the result. All downstream code for ISD::VECTOR_SHUFFLE requires the types to be the same.

Also removed one unnecessary check of matched element counts that was present in the code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188051 91177308-0d34-0410-b5e6-96231b3b80d8