[201811][utilities] advance utilities submodule head

Submodule src/sonic-utilities 2ca1ae1..3ed25a4:
  > Do not start pfcwd for M0 devices (sonic-net#726)
  > Make configlet application script idempotent for updates. (sonic-net#728)

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