Update git submodules

* Update docs/submodules/so.git from branch 'master'
  to 2db91d9f85c272c6d5b05348b358c8b9807fdbc2
  - Merge "Remove useless double assignment in PnfEventReadyDmaapClient.​unregister"
  - Remove useless double assignment in PnfEventReadyDmaapClient.​unregister

    Coverity-scan: CID-211458
    Issue-ID: SO-2211
    Signed-off-by: Artem Naluzhnyy <A.Naluzhnyy@samsung.com>
    Change-Id: I670bb1f5684b90f0d4d01542c77c882e3d4966e4

diff --git a/docs/submodules/so.git b/docs/submodules/so.git
index 92567d2..2db91d9 160000 (submodule)
--- a/docs/submodules/so.git
+++ b/docs/submodules/so.git
@@ -1 +1 @@
-Subproject commit 92567d26641f3a0f127c289e0dad9d86e3b2443c
+Subproject commit 2db91d9f85c272c6d5b05348b358c8b9807fdbc2