base: Fix DPRINTF_UNCONDITIONAL on gem5.fast

Change-Id: I1e559f9c5daae1e9af307cd352791c1b1ac9bbdb
Reviewed-by: Ciro Santilli <ciro.santilli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/23108
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/base/trace.hh

@@ -232,6 +232,7 @@ class Named
 #define DDUMPN(data, count) do {} while (0)
 #define DPRINTFN(...) do {} while (0)
 #define DPRINTFNR(...) do {} while (0)
+#define DPRINTF_UNCONDITIONAL(x, ...) do {} while (0)
 
 #endif  // TRACING_ON