[202012][submodule] Update sonic-swss, sonic-utilities, and sonic-lin…

…ux-kernel submodules (#7064)

sonic-swss
* Add table descriptions for dynamic buffer calculation to the documents (#1664)
* Remove vxlanmgrd dependency on orchagent (#1647)

sonic-utilities
* [show] Fix 'show mac' output, when FDB entry with Vlan 1 is present (#1368)
* [warm-reboot]: Check empty key before issuing redis hget (#1496)
* [generate-dump] Remove Arista specific logic (#1482)
* [warm-reboot]: added automated recover for ISSU file (#1466)
* [warm-reboot] Check if warm restart flag is set when issuing a warm-reboot (#1460)
* [show][config] fix for show/config muxcable hwmode model value; fix show/config muxcable return codes; (#1494)

sonic-linux-kernel
* [net] Disable prio and cls cgroups to make working cgroup2 sock matching (#198)

Signed-off-by: Danny Allen <daall@microsoft.com>