Revert "sonic-sairedis: Add support to sonic-sairedis for gearbox phys"

[daall]

Reverts #624

It looks like the getSwitchType method isn't compatible with the SKUs we use in the VS tests.
https://github.com/Azure/sonic-sairedis/blob/9e2d0c437ca06240b529c3e9ef287c350c02b081/syncd/SaiSwitch.cpp#L140

Logs from https://sonic-jenkins.westus2.cloudapp.azure.com/job/vs/job/sonic-swss-build/1286/:

Jun 27 03:38:01.877260 28c1f78229bb ERR #syncd: :- getSwitchType: failed to get switch type
Jun 27 03:38:01.877351 28c1f78229bb NOTICE #syncd: :- SaiSwitch: constructor took 0.744519 sec
Jun 27 03:38:01.877721 28c1f78229bb ERR #syncd: :- run: Runtime error: :- getSwitchType: failed to get switch type
Jun 27 03:38:01.877750 28c1f78229bb NOTICE #syncd: :- sendShutdownRequest: sending switch_shutdown_request notification to OA for switch: oid:0x0
Jun 27 03:38:01.877857 28c1f78229bb NOTICE #syncd: :- sendShutdownRequestAfterException: notification send successfull
Jun 27 03:38:01.878295 28c1f78229bb INFO #supervisord: orchagent terminate called after throwing an instance of 'std::invalid_argument'
Jun 27 03:38:01.878324 28c1f78229bb INFO #supervisord: orchagent   what():  parse error - unexpected 'o'
Jun 27 03:38:02.052109 28c1f78229bb INFO #supervisord: start.sh orchagent: ERROR (spawn error)

For reference we use the BCM56850 for most of the tests and the MLNX2700 for a few (like test_mirror_ipv6_separate).

I will work on getting these tests added to the sonic-sairedis repo over the weekend so that these are available for PRs going forward. Sorry for the fire drill everyone!