Update git submodules

* Update docs/submodules/qtip from branch 'master'
  - Merge "support rfc2544 test using spirent virtual test center"
  - support rfc2544 test using spirent virtual test center

    1. support rfc2544 throughput and latency test with different packet size
    2. support vswitch performance test based on STCv affinity deployment

    Change-Id: I597de973ab95039dcbcd2da8473a3a5c87a10c14
    Signed-off-by: Qiang Dai <Qiang.Dai@spirent.com>

diff --git a/docs/submodules/qtip b/docs/submodules/qtip
index c29e362..ce37a4f 160000 (submodule)
--- a/docs/submodules/qtip
+++ b/docs/submodules/qtip
@@ -1 +1 @@
-Subproject commit c29e36280713aa232a19e0d3612bae0948601837
+Subproject commit ce37a4fa011c253465f6485dbd05f2c2e99f5109