Fix incorrect ifm and ofm order in delegate

The delegate assumed that the order of the input and output indexes
would stay the same between the Init and Eval call. However, this is not
the case because TFLite will sort the input and output indexes when the
nodes are replaced and the graph gets partitioned.

To handle this, the delegate will now store the initial order of the
input and output indexes before the nodes are replaced.

Change-Id: Ia5e4e218fa2e2ab6e549823c2a43c5380865890f
Signed-off-by: Mikael Olsson <mikael.olsson@arm.com>