[Mellanox] Update SDK to 4.4.2112, FW to *.2008.2112, SAI to 1.18.0

[nazariig]

- Why I did it

• Updated SDK to 4.4.2112, FW to *.2008.2112, SAI to 1.18.0

- How I did it

• Updated the make files with new components versions
• Updated the related submodule pointer

- How to verify it

1. Run regression test on Mellanox platform

- Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006

- Description for the changelog

SDK:

1. New features:

• All | Traps | Added support for L2 IPv6 DHCP Trap.
• All | Buffer | Added support for shared headroom.
• SPC1 | Modules | Added support for 40GbE SWDM4 modules on SN2700 system.
• SPC2 | Cables | Added support for passive copper splitter cables 200Gbe to 4x50GbE on SN3700 systems.
• SPC3 | Cables and Transceivers | Added support for 100GbE optical transceiver MMA1L30-XX for connectivity between SN2700 leaves and a SN4700 spine.
• SPC3 | Modules | Added support for 100GbE CWDM transceiver MMA1L30-CM on SN4700 system.

2. Bugs fixes:

• All | Driver | When sending a control packet that is larger than the port MTU, the control-sending queue will get stuck.
• All | Link operation | When link drops from Active to Polling, operational speed will not be cleared (i.e. it will continue showing the last active state).
• SPC3 | When connecting SN4700 with Cisco 3432C using 400GbE, link does not rise in the corner port when using auto-negotiation.
• SPC3 | On rare occasion, on SN4700 systems, link up on DR4 modules may up to 10 minutes.
• SPC2 | On rare occasions packets loss may be experienced on SN3800 due to signal integrity issues.
• ISSU | On Spectrum systems, ISSU is not supporting the creation of additional VLANs from what used to exist the during ISSU reconfiguration stage.

SAI:

• Add AzD Policy based hash static (SPC2+)
• Add VXLAN diff tool
• Add CRM by generic API (sai_object_type_get_availability)
• Add PFC pause duration in us
• Create 3 FW dumps instead of 1 in saidump
• Reduce verbosity for clear pool stats message
• Update SAI headers to release v1.6.6 (needed for AzD dynamic) + pause duration us change
• Shared headroom pool
• Policy based hash action optimization

- A picture of a cute animal (not mandatory but encouraged)

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[nazariig]

sonic-net/sonic-sairedis#733

[liat-grozovik]

retest vsimage please