gpu: nova-core: fix layout of NV_PMC_BOOT_0

The layout of NV_PMC_BOOT_0 has two small issues:

- The "chipset" field, while useful to identify a chip, is actually an
  aggregate of two distinct fields named "architecture" and
  "implementation".
- The "architecture" field is split, with its MSB being at a different
  location than the rest of its bits.

Redefine the register layout to match its actual definition as provided
by OpenRM and expose the fully-constructed "architecture" field through
our own "Architecture" type. The "chipset" pseudo-field is also useful
to have, so keep providing it.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Link: https://lore.kernel.org/r/20250507-nova-frts-v3-6-fcb02749754d@nvidia.com


[ Use Result from kernel::prelude. - Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>