Revert "Ensure that GT_CNS_VEC is handled in LinearScan::isMatchingConstant (#70171)"

This reverts commit 24f5de4.

Author: kunalspathak

src/coreclr/jit/codegenarmarch.cpp

@@ -144,7 +144,7 @@ void CodeGen::genCodeForTreeNode(GenTree* treeNode)
     if (treeNode->IsReuseRegVal())
     {
         // For now, this is only used for constant nodes.
-        assert(treeNode->OperIs(GT_CNS_INT, GT_CNS_DBL, GT_CNS_VEC));
+        assert((treeNode->OperGet() == GT_CNS_INT) || (treeNode->OperGet() == GT_CNS_DBL));
         JITDUMP("  TreeNode is marked ReuseReg\n");
         return;
     }

src/coreclr/jit/lsra.cpp

@@ -2706,7 +2706,6 @@ bool LinearScan::isMatchingConstant(RegRecord* physRegRecord, RefPosition* refPo
             }
             break;
         }
-
         case GT_CNS_DBL:
         {
             // For floating point constants, the values must be identical, not simply compare
@@ -2718,12 +2717,6 @@ bool LinearScan::isMatchingConstant(RegRecord* physRegRecord, RefPosition* refPo
             }
             break;
         }
-
-        case GT_CNS_VEC:
-        {
-            return GenTreeVecCon::Equals(refPosition->treeNode->AsVecCon(), otherTreeNode->AsVecCon());
-        }
-
         default:
             break;
     }

src/coreclr/jit/lsraxarch.cpp

@@ -147,7 +147,6 @@ int LinearScan::BuildNode(GenTree* tree)
         case GT_CNS_INT:
         case GT_CNS_LNG:
         case GT_CNS_DBL:
-        case GT_CNS_VEC:
         {
             srcCount = 0;
             assert(dstCount == 1);