Fix bug in ufdt_get_node_by_phandle

Bug:67779848
Test: mm

If the phandle being searched for exceeded the highest phandle
in phandle_table.data, the bug was causing the return of the node
corresponding to the highest phandle in phandle_table.data.

Change-Id: I731c820b0c4bfe75a14cc1d22a34262b9905f365