Fix casette sense switch input

vic20/vic20.vhd

@@ -292,7 +292,7 @@ begin
   cass_read <= '0';
   --<= cass_write;
   --<= cass_motor
-  cass_sw <= '0'; --'1'; -- motor off
+  cass_sw <= '1'; -- sense casette buttons
 
   -- serial
 --  serial_srq_in <= '1';