Remove uses of WITH_X509

Remove uses of WITH_X509

GetCredEntryByCredId was using WITH_X509 instead of WITH_DTLS,
causing a block of code to not be included in certain build
configurations.

Change-Id: I16c05f38c7d2e317a727d6480289151e30229d71
Signed-off-by: Greg Zaverucha <gregz@microsoft.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/18581
Reviewed-by: Kevin Kane <kkane@microsoft.com>
Reviewed-by: Alex Kelley <alexke@microsoft.com>
Tested-by: jenkins-iotivity <jenkins@iotivity.org>
Reviewed-by: Nathan Heldt-Sheller <nathan.heldt-sheller@intel.com>