[202012][swss][utilities] advance submodule heads

utilities:
* 83f068b 2021-03-22 | Handling error scenario of adding port to Vlan which is part of LAG (sonic-net#1516) (HEAD -> 202012) [Sudharsan Dhamal Gopalarathnam]
* 470e8ce 2021-03-24 | Enable PFCWD only on ports where PFC is enabled (sonic-net#1508) [Andriy Yurkiv]
* 09ef2e0 2021-03-22 | [show][config] add support for setting and displaying switching modes on Y cable (sonic-net#1501) [vdahiya12]
* 0d17d37 2021-03-24 | Warmboot script improvements - timeout exec, disable swss autorestart, remove trap (sonic-net#1495) [Vaibhav Hemant Dixit]
* 2718cd8 2021-03-24 | [show] Fix int status of LAGs, configured as Vlan members (sonic-net#1478) [maksymbelei95]
* cc168fb 2021-03-22 | Fix bug: show vlan config for vlan with no members (sonic-net#1503) [allas-nvidia]

swss:
* 5d8d1fb 2021-03-26 | Revert "Revert "[buffermgr] Support maximum port headroom checking (sonic-net#1607)" (sonic-net#1675)" (sonic-net#1682) (HEAD -> 202012) [Prince Sunny]
* f8df1f8 2021-03-26 | [Dynamic Buffer Calc] Enhance the field checking in table handling (sonic-net#1680) [Stephen Sun]
* 6328c9f 2021-03-22 | [MuxOrch] FDB ageout safety check (sonic-net#1674) [Prince Sunny]
* e1d733e 2021-03-21 | reduce severity of log to info in case of flush on non-existing member (sonic-net#1669) [allas-nvidia]

Signed-off-by: Ying Xie <ying.xie@microsoft.com>