Update git submodules

* Update docs/submodules/qtip from branch 'master'
  - Fix bug that start_job script exit unexpectedly

    When `set -o errexit` is enabled in script, the non-zero return value
    from `diff` is considered as an error. But actually diff returns 1 when
    difference is found. The error exit option should be disabled when dealing
    `diff`.

    Change-Id: I6270ec8f7036b3d752736a80474468e26a613585
    Signed-off-by: Yujun Zhang <zhang.yujunz@zte.com.cn>

diff --git a/docs/submodules/qtip b/docs/submodules/qtip
index acf3b4f..b15b028 160000 (submodule)
--- a/docs/submodules/qtip
+++ b/docs/submodules/qtip
@@ -1 +1 @@
-Subproject commit acf3b4ff0b556e121d665e31e893c8dc1159f034
+Subproject commit b15b028f061858de71fc98459d562dd76e3aecfe