mlx5_core: Add OFED-only sysfs files and commands

[saviramnvidia]

Enhance the mlx5_core plugin with OFED-specific
features and improve OpenVSwitch sFlow collection.

mlx5_core plugin enhancements:

• Add ethtool RSS hash collection (ethtool -x) for all ethernet devices
• Add ethtool firmware dump support (ethtool -w) with deprecation notice for kernels >= 6.1
• Add optional firmware dump data collection via --firmware-dump option
• Add sysfs path collection organized by category:
  • Network device settings: hairpin counters, rate limiting, local loopback
  • SR-IOV and VF configurations: meters, VLAN, config
  • InfiniBand settings: TTL and traffic class overrides
  • devlink compatibility paths

OpenVSwitch plugin enhancement:

• Add sFlow configuration collection (ovs-vsctl list sflow)

---

Please place an 'X' inside each '[]' to confirm you adhere to our Contributor Guidelines

• Is the commit message split over multiple lines and hard-wrapped at 72 characters?
• Is the subject and message clear and concise?
• Does the subject start with [plugin_name] if submitting a plugin patch or a [section_name] if part of the core sosreport code?
• Does the commit contain a Signed-off-by: First Lastname email@example.com?
• Are any related Issues or existing PRs properly referenced via a Closes (Issue) or Resolved (PR) line?
• Are all passwords or private data gathered by this PR obfuscated?

[dickmanmaor]

Any plan for mlxdevm plugin?

[dickmanmaor]

split to different patch