fix code for Solution 198 (golang)

Author: lightfish-zhang

solution/0198.House Robber/Solution.go

@@ -6,7 +6,7 @@
 func rob(nums []int) int {
 	x, y := 0, 0
 	for _, n := range nums {
-		x, y = y, x+y
+		x, y = y, x+n
 		if x > y {
 			y = x
 		}