remove the page map kernel object pointer that is embedded into the page table entries

[rottaran]

Each page table is followed by capability entries and these somewhat point to the owning page map object anyway. Just look into the first capability entry's object pointer and add some type-casting because we know the actual type behind the IKernelObject*. It contains the pointer to the actual page map kernel object. Make sure that the first cap entry is always initalized correctly.