[systemtest] Run OTBN RSA test on Nexys Video in CI

Enable the end-to-end RSA test in FPGA CI. It takes a while to run in
Verilator simulation, but it's quick to run on FPGAs, giving us good
test coverage and fast test turnaround at the same time.

Fixes #3691

Signed-off-by: Philipp Wagner <phw@lowrisc.org>
diff --git a/test/systemtest/config.py b/test/systemtest/config.py
index 0677548..b63a7ef 100644
--- a/test/systemtest/config.py
+++ b/test/systemtest/config.py
@@ -35,6 +35,12 @@
         "verilator_extra_args": ['+OTBN_USE_MODEL=1'],
         "targets": ["sim_verilator"],
     },
+    # The RSA tests can be run in simulation, but take a long time there. Run
+    # them on FPGAs only for faster test results.
+    {
+        "name": "otbn_rsa_test",
+        "targets": ["fpga_nexysvideo"],
+    },
     {
         "name": "dif_otp_ctrl_smoketest",
     },