gpu: nova-core: add delimiter for helper rules in register!() macro

This macro is pretty complex, and most rules are just helper, so add a
delimiter to indicate when users only interested in using it can stop
reading.

Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Link: https://lore.kernel.org/r/20250619-nova-frts-v6-7-ecf41ef99252@nvidia.com
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

Author: Gnurou

drivers/gpu/nova-core/regs/macros.rs

@@ -94,6 +94,8 @@ macro_rules! register {
         register!(@io$name @ + $offset);
     };
 
+    // All rules below are helpers.
+
     // Defines the wrapper `$name` type, as well as its relevant implementations (`Debug`, `BitOr`,
     // and conversion to regular `u32`).
     (@common $name:ident $(, $comment:literal)?) => {