scripts: size_report: Fix tree build for symbol copies

Fix the memory footprint tree build for symbols with copies,
e.g. static inline functions which are local per each compilation
unit. Copies have the same path and symbol name, but different
memory blocks associated, so they have to have separate nodes.
Before the fix, these copies were merged into one node, with
summary size and memory address of one of the symbols.

Signed-off-by: Dmitrii Golovanov <dmitrii.golovanov@intel.com>