Fix some sizeof and switch-case issues.

These issues were detected by CodeChecker. CodeChecker is a python application that runs static analyzers on the codebase.

You can view a list of reported codechecker issues here: http://codechecker.bpodrygajlo.com/openairinterface5g/reports?review-status=Unreviewed&review-status=Confirmed%20bug&detection-status=New&detection-status=Reopened&detection-status=Unresolved&run=initial_report. The login/password is guest/guest.