[Filesystem][Alarm] Fix coverity/SVACE issues

[Filesystem][Alarm] Fix coverity/SVACE issues

[Bug] Fixed Coverity issues: 119865, 119863.
  Fixed SVACE issue: 345864

  Issues were related to not reachable code (invalid returned value was checked)
  in Alarm module and not checking returned values in Filesystem module.
  SVACE issue 345864 is related to the same problem as Coverity 119863.

[Verification] Code compiles without errors.
  TCT passrate for Alarm and Filesystem - 100%.

Change-Id: I315d0aed94f8efef13d37a73b313ef455fb3b00e
Signed-off-by: Piotr Kosko <p.kosko@samsung.com>