vfio-ccw: Remove pfn_array_table

Now that both CCW codepaths build this nested array:

  ccwchain->pfn_array_table[1]->pfn_array[#idaws/#pages]

We can collapse this into simply:

  ccwchain->pfn_array[#idaws/#pages]

Let's do that, so that we don't have to continually navigate two
nested arrays when the first array always has a count of one.

Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <20190606202831.44135-8-farman@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>