Responder: simplify if-else structure in sss_dp_get_account_msg()
The structure of if-else statements in sss_dp_get_account_msg
become too complex. Replacing if-else with switch initially,
Will investigate more on refactoring further.
Resolves: https://pagure.io/SSSD/sssd/issue/1903
Reviewed-by: Fabiano FidĂȘncio <fidencio@redhat.com>