Default to loading the otp bitstream

Change-Id: I70bc612636c3635921af768fbf585eb7d433fbe9

platforms/nexus/setup.sh

diff --git a/platforms/nexus/setup.sh b/platforms/nexus/setup.sh
index 9b27f13..53fc866 100644
--- a/platforms/nexus/setup.sh
+++ b/platforms/nexus/setup.sh
@@ -240,13 +240,10 @@
     local bitstream_path="$(realpath $1)"
     if [[ -z "${bitstream_path}" ]]; then
         (
-            echo "Usage: nexus_load_bitstream path/to/file.bit"
-            echo
-            echo "Loads bitstream file onto Nexus FPGA"
-            echo "This command may ask you for the Nexus SOM root password"
-            echo
+            echo "WARNING: No bitstream specified. Loading default bitstream"
+            echo "from \$OUT/hw/bitstream/vivado/fpga_nexus_mask_test_rom.bit"
         ) | fmt
-        return 1
+        bitstream_path="${OUT}/hw/bitstream/vivado/fpga_nexus_mask_test_rom.bit"
     fi
 
     if [[ -z "${NEXUS_ID}" ]]; then