Lost fix to nodemcu-partition.py (take 2) (#3139)

Replay a line from #2861
after accidental revert in
#3075 (specifically
9ef5c7d)

Author: nwf

tools/nodemcu-partition.py

@@ -126,7 +126,7 @@ def load_PT(data, args):
     """
 
     PTrec,recs = unpack_RCR(data)
-    flash_size = fs.args if args.fs is not None else DEFAULT_FLASH_SIZE
+    flash_size = args.fs if args.fs is not None else DEFAULT_FLASH_SIZE
 
     # The partition table format is a set of 3*uint32 fields (type, addr, size),
     # with the optional last slot being an end marker (0,size,0) where size is