#### Why I did it
Add platform_asic file to each platform folder in sonic-device-data package. The file content will be used as the ground truth of mapping from PLATFORM_STRING to switch ASIC family.
One use case of the mapping is to prevent installing a wrong image, which targets for other ASIC platforms. For example, currently we have several ONIE images naming as sonic-*.bin, it's easy to mistakenly install the wrong image. With this mapping built into image, we could fetch the ONIE platform string, and figure out which ASIC it is using, and check we are installing the correct image.
After this PR merged, each platform vendor has to add one mandatory text file `device/PLATFORM_VENDOR/PLATFORM_STRING/platform_asic`, with the content of the platform's switch ASIC family.
I will update https://github.com/Azure/SONiC/wiki/Porting-Guide after this PR is merged.
You can get a list of the ASIC platforms by `ls -b platform | cat`. Currently the options are
```
barefoot
broadcom
cavium
centec
centec-arm64
generic
innovium
marvell
marvell-arm64
marvell-armhf
mellanox
nephos
p4
vs
```
Also support
```
broadcom-dnx
```
#### How I did it
#### How to verify it
Test one image on DUT. And check the folders under `/usr/share/sonic/device`
- Why I did it
Update platform data files for SN4800 to support chassis management
- How I did it
Update pcie.yml
Update sensors.conf
Update platform.json
- How to verify it
Run platform test suite in sonic-mgmt
- Why I did it
To create SDK dump on Mellanox devices when SDK event has occurred.
- How I did it
Set the SKUs keys needed to initialize the feature in SAI.
- How to verify it
Simulate SDK event and check that dump is created in the expected path.
- Why I did it
Add initial support of SN4800 platform .
NOTE: This is work in progress and not full support of the platform.
- How I did it
Add new folders for SN4800 with zero ports based on SN4700 Spectrum-3 switch.
- How to verify it
Simulator device was tested. See #7448
