Update 0056.合并区间.md

Update Java solution. For sorting, no need to compare the second element in an interval.

problems/0056.合并区间.md

@@ -144,11 +144,7 @@ class Solution {
         Arrays.sort(intervals, new Comparator<int[]>() {
             @Override
             public int compare(int[] o1, int[] o2) {
-                if (o1[0] != o2[0]) {
                 return Integer.compare(o1[0], o2[0]);
-                } else {
-                    return Integer.compare(o1[1],o2[1]);
-                }
             }
         });