[CostModel][X86] Removed unused cost. NFCI.

SHL v8i32 is already handled in the SSE41 cost table

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@292612 91177308-0d34-0410-b5e6-96231b3b80d8

Author: RKSimon

lib/Target/X86/X86TargetTransformInfo.cpp

@@ -611,7 +611,6 @@ int X86TTIImpl::getArithmeticInstrCost(
     { ISD::SHL,  MVT::v16i8,    26 }, // cmpgtb sequence.
     { ISD::SHL,  MVT::v8i16,    32 }, // cmpgtb sequence.
     { ISD::SHL,  MVT::v4i32,   2*5 }, // We optimized this using mul.
-    { ISD::SHL,  MVT::v8i32, 2*2*5 }, // We optimized this using mul.
     { ISD::SHL,  MVT::v2i64,     4 }, // splat+shuffle sequence.
     { ISD::SHL,  MVT::v4i64,   2*4 }, // splat+shuffle sequence.