Update git submodules

Update git submodules

* Update docs/submodules/so.git from branch 'master'
  to f697af873b2ced50e2f23a2170a1d1889f0b6ab1
  - Merge "Added null check for listFiles() result to prevent crash at iterating through file list; replaced System.out.println calls with logger calls"
  - Added null check for listFiles() result to prevent crash
    at iterating through file list; replaced System.out.println
    calls with logger calls

    Issue-ID: SO-1841
    Signed-off-by: Oleksandr Moliavko <o.moliavko@samsung.com>
    Change-Id: I6b4a49228903f013127b39244db9d1b67c0ff2f0