Broken definition DP_IS_END_TYPE

Forwarded from [Debian bug](https://bugs.debian.org/977478):

in line 71, there is the macro definition

```
#define DP_IS_END_TYPE(a)
```

Obviously, the empty string is not a valid expression to test whether the
lower seven bits of a are set, this should probably read

```
#define DP_IS_END_TYPE(a) (DevicePathType(a) == END_DEVICE_PATH_TYPE)
```