Given a 2D matrix A and an integer K, find the max sum of A's sub-matrix. The max sum should be no larger than K.

Example:

```
Given A = [
[-1, 0, 1],
[0, -2, 3]
]
K = 2
```

The answer is 2. Because the sum of sub-matrix`[[0, 1], [-2, 3]]`

is 2 and 2 is the max number no larger than K(K = 2).