PROC GEOCODE does recognize standard abbreviations for street types, e.g. Ln or Ln. for Lane. All of the supported types are in the SASHELP.GCTYPE data set.
If you have other street types not included, you can copy SASHELP.GCTPYE to another library and add them. Just make sure to sort the updated data set by NAME and then rebuild the simple index on that variable. Then, when submitting your PROC GEOCODE run, include the TYPE= option to use your new street type data set. See the PROC GEOCODE documentation for details on this option.