platform/mellanox: mlxreg-dpu: Add initial support for Nvidia DPU

platform/mellanox: mlxreg-dpu: Add initial support for Nvidia DPU

Provide platform support for Nvidia (DPU) Data Processor Unit for the
Smart Switch SN4280.

The Smart Switch equipped with:
- Nvidia COME module based on AMD EPYC™ Embedded 3451 CPU.
- Nvidia Spectrum-3 ASIC.
- Four DPUs, each equipped with Nvidia BF3 ARM based processor and
  with Lattice LFD2NX-40 FPGA device.
- 28xQSFP-DD external ports.
- Two power supplies.
- Four cooling drawers.

Driver provides support for the platform management and monitoring
of DPU components. It includes support for: health events, resets and
boot progress indications logic, implemented by FPGA device.

Reviewed-by: Ciju Rajan K <crajank@nvidia.com>
Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
[ij: added depends on I2C]
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20250421092051.7687-2-vadimp@nvidia.com
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>