of: overlay: add overlay unittest data for node names and symbols

Add nodes and properties to overlay_base and overlay dts files to
test for
   - incorrect existing node name detection when overlay node name
     has a unit-address
   - adding overlay __symbols__ properties to live tree when an
     overlay is added to the live tree

The following console messages will appear near the end of unittest
until the code errors are corrected:

   OF: Duplicate name in fairway-1, renamed to "ride@100#1"

   ### dt-test ### FAIL of_unittest_overlay_high_level():2296 Adding overlay 'overlay_bad_symbol' failed

   ### dt-test ### end of unittest - 190 passed, 1 failed

Signed-off-by: Frank Rowand <frank.rowand@sony.com>
Signed-off-by: Rob Herring <robh@kernel.org>