perf script python: Rename call-graph-from-postgresql.py to call-graph-from-sql.py

Rename call-graph-from-postgresql.py to call-graph-from-sql.py in
preparation for adding support to it for SQLite 3.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Link: http://lkml.kernel.org/r/1501749090-20357-5-git-send-email-adrian.hunter@intel.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>