variables: FLOORPLAN_DEF is also used in place stage

See flow/scripts/global_place_skip_io.tcl which references
this variable too. Without the change, pin definitions in the
DEF are simply ignored.

Signed-off-by: Sylvain Munaut <[email protected]>

Author: smunaut

flow/scripts/variables.yaml

@@ -184,6 +184,7 @@ FLOORPLAN_DEF:
     Use the DEF file to initialize floorplan.
   stages:
     - floorplan
+    - place
 REMOVE_ABC_BUFFERS:
   description: >
     Remove abc buffers from the netlist.