[sonic-swss] submodule update

Signed-off-by: Andriy Yurkiv <ayurkiv@nvidia.com>

d8ca31c (origin/master, origin/HEAD, master) [vnet/vxlan] Add support of multiple mappers for the VxLAN tunnel (sonic-net#1843)
7280e19 [orchagent][ports] Add port reference increment / decrement to lag member add / remove flows (sonic-net#1825)
0217b66 [nhg]: Add support for weight in nexthop group member. (sonic-net#1853)
df96059 VOQ: Nexthop for remote VOQ LC should be created on inband OIF. (sonic-net#1823)
8f7ea14 Code changes to support IPv6 Link local enhancements (sonic-net#1463)
8674b3c Open record file in append mode (sonic-net#1845)