Fix security server API argument validation

Fix security server API argument validation

[Issue#]       SSDWSSP-332
[Bug]          Potential bug, bad parameters (f.e. pid) may be used in two
               functions.
[Cause]        Two API functions does not validate all given arguments.
               Also there is a risk of unsigned int overflow when calculating
               password validity (when changing from days to seconds).
[Solution]     Checking existence of a process with given pid added.
               Unsigned int overflow protection is added.
               Also argument validation added to API function.
[Verification] Build, install and run tests.

Change-Id: Ia8e9528462e31220faf88c72c111b7f0efc03681