Remove redundant not-null test

Reported-by: Ranier Vilela

Discussion: https://postgr.es/m/MN2PR18MB2927E73FADCA8967B2302469E3490@MN2PR18MB2927.namprd18.prod.outlook.com

Author: Ranier Vilela

Backpatch-through: master

src/backend/executor/execExpr.c

@@ -2434,7 +2434,7 @@ ExecComputeSlotInfo(ExprState *state, ExprEvalStep *op)
 	{
 		desc = parent->scandesc;
 
-		if (parent && parent->scanops)
+		if (parent->scanops)
 			tts_ops = parent->scanops;
 
 		if (parent->scanopsset)