Fix two enumeration types in function signatures

Spotted with clang and "-Wconversion".

Signed-off-by: Lukas Fleischer <calcurse@cryptocrack.de>

src/ical.c

@@ -773,7 +773,7 @@ ical_read_exdate(llist_t * exc, FILE * log, char *exstr, unsigned *noskipped,
 
 /* Return an allocated string containing the name of the newly created note. */
 static char *ical_read_note(char *line, unsigned *noskipped,
-                            ical_vevent_e item_type, const int itemline,
+                            ical_types_e item_type, const int itemline,
                             FILE * log)
 {
   char *p, *notestr, *note;

src/io.c

@@ -932,7 +932,7 @@ void io_export_data(enum export_type type)
   }
 }
 
-static FILE *get_import_stream(enum export_type type)
+static FILE *get_import_stream(enum import_type type)
 {
   FILE *stream = NULL;
   char *stream_name;