[202012][swss][utilities] advance submodule heads (#7267)

SWSS:
* d97c7c7 2021-04-07 | [Dynamic Buffer Calc] Enhancement: coding style and LGTM alerts (#1693) (HEAD -> 202012) [Stephen Sun]
* f70b3da 2021-04-03 | [Makefile] Reorder libsaimetadata and libswsscommon (#1689) [Kamil Cudnik]
* 72ae85d 2021-04-08 | [vlan] Add support of VLAN host interface (#1645) [Volodymyr Samotiy]
* a555b9c 2021-04-02 | Correct the sflow default sample rate (#1623) [fredyu190011]

Utilities:
* 1a789d2 2021-04-07 | Fixed the possibility of using uninitialized variable in route_check.py (#1551) (HEAD -> 202012) [Renuka Manavalan]
* 2412e3c 2021-04-06 | Fix fast-reboot-dump.py SonicV2Connector after late merge (#1546) [shlomibitton]
* f99c5f1 2021-04-02 | [fast-reboot] Fix dump script to support PortChannels in a VLAN group (#1393) [shlomibitton]
* 716e2af 2021-04-04 | Reduce time taken by show commands on multi-asic platforms (#1544) [abdosi]
* a160519 2021-04-03 | [setup.py]: move the module to test requirement (#1542) [lguohan]
* eaa67fe 2021-04-04 | [config] Eliminate race condition between reloading Monit config and (#1543) [yozhao101]
* 2497a9e 2021-04-03 | [reboot] No need enable the Linux magic system request key (#1538) [yozhao101]
* 9fda6fe 2021-04-06 | [fwutil]: Fix next image mount (#1533) [Nazarii Hnydyn]
* 9af50fe 2021-02-09 | Import 'mock' module from 'unittest' library (#1415) (HEAD -> 202012) [Joe LeVeque]

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