Lower asap7/cva6 placement density

After the don't use change the mapping to standard cells is denser. For
the area coming out of synthesis we have

   Chip area for module '\cva6': 14649.248080
     of which used for sequential elements: 3027.420360 (20.67%)

vs previously

   Chip area for module '\cva6': 17152.298740
     of which used for sequential elements: 3027.420360 (17.65%)

At the same time RD placement struggles with the new netlist. We can
lower the placement density to work around and still fit into the
original die size.

Signed-off-by: Martin Povišer <[email protected]>

Author: povik

flow/designs/asap7/cva6/config.mk

@@ -91,7 +91,7 @@ export SDC_FILE               = $(DESIGN_HOME)/$(PLATFORM)/$(DESIGN_NAME)/constr
 export CORE_UTILIZATION       = 70
 export CORE_MARGIN            = 2
 export MACRO_PLACE_HALO       = 3 3
-export PLACE_DENSITY          = 0.73
+export PLACE_DENSITY          = 0.67
 
 # a smoketest for this option, there are a
 # few last gasp iterations