gowin: Speed up the GUI
gowin: Speed up the GUI

By mistake, an empty decal gets filled with graphical elements.

Signed-off-by: YRabbit <6d0ebbbdce32474db8141d23d2c01bd9628d6e5f@yrabbit.cyou>

YosysHQ/nextpnr,YosysHQ/nextpnr,YosysHQ/nextpnr,YosysHQ/nextpnr