base,dev: Use the standard attribute [[noreturn]].

The [[noreturn]] attribute has been standard since c++11, and so we
don't (and haven't for a while) need to wrap it in a macro.

Change-Id: Ifba62c87c19224bb366e93ebba685a063cc750ce
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/35218
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/dev/arm/gpu_nomali.hh

@@ -99,7 +99,7 @@ class NoMaliGpu : public PioDevice
      * @param err Error code from the NoMali library.
      * @param msg Message to print.
      */
-    static void gpuPanic(nomali_error_t err, const char *msg) M5_ATTR_NORETURN;
+    [[noreturn]] static void gpuPanic(nomali_error_t err, const char *msg);
     /**
      * Panic if the NoMali returned an error, do nothing otherwise.
      *