[otbnsim] Editorial message fix

Signed-off-by: Philipp Wagner <phw@lowrisc.org>
diff --git a/hw/ip/otbn/dv/otbnsim/sim/stats.py b/hw/ip/otbn/dv/otbnsim/sim/stats.py
index 9fa1d89..23c1948 100644
--- a/hw/ip/otbn/dv/otbnsim/sim/stats.py
+++ b/hw/ip/otbn/dv/otbnsim/sim/stats.py
@@ -275,7 +275,7 @@
                 f"(no function prologue/epilogue needed)\n")
         out += (f"Overall, {total_calls_req_call} of {total_func_calls} "
                 f"({(total_calls_req_call / total_func_calls * 100):.02f} "
-                f"percent) need full function call semantics.\n")
+                f"percent) calls need full function call semantics.\n")
 
         return out