Update git submodules

* Update docs/submodules/music.git from branch 'master'
  to 4771ff0c0b5b68209e29bec88a0b2e566ef50834
  - Merge "Fixed Sonar issues in ZkStatelessLockService"
  - Fixed Sonar issues in ZkStatelessLockService

    Fixed potential NullPointerException.
    Added restoring of the interrupted state.
    Removed unnecessary imports.
    Added missing loggers.

    Change-Id: I62bb8ef2b4893c60c1cea7dcd4ba29f2908b4d05
    Issue-ID: MUSIC-329
    Signed-off-by: Robert Bogacki <r.bogacki@samsung.com>

diff --git a/docs/submodules/music.git b/docs/submodules/music.git
index c912159..4771ff0 160000 (submodule)
--- a/docs/submodules/music.git
+++ b/docs/submodules/music.git
@@ -1 +1 @@
-Subproject commit c91215965fa4d6f19441fa96fd5c3b5910795057
+Subproject commit 4771ff0c0b5b68209e29bec88a0b2e566ef50834