gpu: nova-core: impl From for u32 for enums used from register!

Implement From for u32 for all enum types used within the register!()
macro.

This avoids a conflict with [1] as reported in [2].

Cc: Alexandre Courbot <acourbot@nvidia.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Link: https://lore.kernel.org/r/20250615-ptr-as-ptr-v12-5-f43b024581e8@gmail.com [1]
Link: https://lore.kernel.org/all/20250624173114.3be38990@canb.auug.org.au/

 [2]
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Tested-by: Alexandre Courbot <acourbot@nvidia.com>
Link: https://lore.kernel.org/r/20250624132337.2242-1-dakr@kernel.org


Signed-off-by: Danilo Krummrich <dakr@kernel.org>