cifs: fix underflow in parse_server_interfaces()

In the Linux kernel, the following vulnerability has been resolved: cifs: fix underflow in parse_server_interfaces() In this loop, we step through the buffer and after each item we check if the size_left is greater than the minimum size we need. However, the problem is that "bytes_left" is type ssize_t while sizeof() is type size_t. That means that because of type promotion, the comparison is done as an unsigned and if we have negative bytes left the loop continues instead of ending.