perf s390: Fix reading cpuid model information

Commit eca0fa28 (perf record: Provide detailed information on s390
CPU") fixed a  build error on Ubuntu. However the fix uses the wrong
size to print the model information.
Signed-off-by: Thomas Richter <tmricht@linux.vnet.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Fixes: eca0fa28 ("perf record: Provide detailed information on s390 CPU")
Link: http://lkml.kernel.org/r/20180219102444.96900-1-tmricht@linux.vnet.ibm.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/arch/s390/util/header.c

@@ -81,7 +81,7 @@ int get_cpuid(char *buffer, size_t sz)
 			line2 = line + strlen(SYSINFO_MODEL);
 
 			while ((cp = strtok_r(line2, "\n ", &line2))) {
-				mdsize += scnprintf(model + mdsize, sizeof(type) - mdsize,
+				mdsize += scnprintf(model + mdsize, sizeof(model) - mdsize,
 						    "%s%s", model[0] ? "," : "", cp);
 			}
 			break;