SP int: stop CodeSonar complaining about i being negatve

[SparkiDev]

Description

n is checked for negative and fail out in that case.
i is n devided by a positive constant and can never be negative.

Testing

Standard testing.

Checklist

• added tests
• updated/added doxygen
• updated appropriate READMEs
• Updated manual and documentation

[SparkiDev]

cavp code fails to build.

[dgarske]

Retest this please:

PRB-fips-repo-and-harness-test-v3-part2
FIPS testing-140-3-tail
...
-------------------- TEST CSending interrupt signal to process
Sending interrupt signal to process
Sending interrupt signal to process
Sending interrupt signal to process
Terminated
script returned exit code 143