[sonic-swss] Update submodule (#5231)

* src/sonic-swss d2bab10...c4949a2 (34):
  > [dvs] Add new common issues and TOC to DVS README (#1405)
  > Avoid adding loopback interface (ip link add) when setting nat zone on loopback interface (#1411)
  > [portsorch] add buffer drop FC group (#1368)
  > [dvs/chassis] Bring up SONiC interfaces in virtual chassis (#1410)
  > [chassis/dvs] Add support for virtual chassis to DVS testbed (#1345)
  > [sonic-swsss] Fix the issue of field "next_hop_ip" not getting updated in state DB in ERSPAN Mirror (#1375)
  > [intfmgr] Fix OA crash issue due to link local configurations (#1195)
  > Fix the issue when persistent DVS is used to run pytest which has number of front-panel ports < 32 (#1373)
  > [dvs] Refactor AsicDbValidator (#1402)
  > [fec] Get FEC mode when port is already admin down (#1403)
  > [fec] added logic that put port down before applying fec onfiguration (#1399)
  > [dvs] Add performance test for adding and deleting routes (#1392)
  > Ignore IPv6 link-local and multicast entries as Vnet routes (#1401)
  > [vlanmgr] Support Jumbo Frame By Default (#1393)
  > Fix log/syslog not being correct when last test fails for given module (#1395)
  > Get initial speed from ASIC DB  (#1390)
  > [dvs] Add options to limit CPU usage (#1394)
  > [intfsorch] Retrieve Port object before setting NAT zone on router interfaces. (#1372)
  > [.gitignore] Ignore gearsyncd binary (#1381)
  > Added Max Nexthopgroup/ECMP Count supported by device into State DB. (#1383)
  > [dvs] Upload logs even if failure occurs during startup (#1389)
  > [rates] fix issue with rates init (#1387)
  > [dvs] Validate that SWSS is ready to receive input before starting tests (#1385)
  > [dvs] Convert sflow and speed tests to use dvslib (#1382)
  > [dvs_acl] Refactor and document dvs_acl library (#1378)
  > [dvs] Fix install instructions in README (#1379)
  > [dvs] Update README with new flags, options, and known issues (#1380)
  > swss: gearsyncd should return 0 on exit (#1376)
  > Remove 00-copp.config.json from swss debian package. (#1366)
  > fix undefined var in rates lua scripts (#1365)
  > [fdborch] Fixed Orchagent crash in FDB flush on port disable. (#1369)
  > [tlm_teamd]: Try to add LAG again, when teamd is not ready first time (#1347)
  > [vs] Incorporate python3 best practices into DVSLib (#1357)
  > [dvs] Mark unstable tests as xfail (#1356)