ranap ASN.1: Define IMSI as OCTET STRING to work around asn1c bug

When IMSI is a TBCD-STRING type, and TBCD-STRING is defined as OCTET
STRING, we end up encoding the IMSI the wrong way.  I don't knwo why
that is, but changing it fixed the problem, as described below:

before this commit:
00 17                           PeranentNAS-UE-ID
40                              criticality ignore
0a                              (length)
00                              presence = IMSI
08                              BUG: why the additional length field?
46 23 91 34 70 77 80 f3         IMSI (643219430777083)

after this commit:
00 17                           PeranentNAS-UE-ID
40                              criticality ignore
09                              (length)
50                              presence = IMSI
46 23 91 34 70 77 80 f3         IMSI (643219430777083)
diff --git a/src/ranap/RANAP_IMSI.h b/src/ranap/RANAP_IMSI.h
index 6cf720d..747c546 100644
--- a/src/ranap/RANAP_IMSI.h
+++ b/src/ranap/RANAP_IMSI.h
@@ -12,14 +12,14 @@
 #include <asn_application.h>
 
 /* Including external dependencies */
-#include "RANAP_TBCD-STRING.h"
+#include <OCTET_STRING.h>
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 /* RANAP_IMSI */
-typedef RANAP_TBCD_STRING_t	 RANAP_IMSI_t;
+typedef OCTET_STRING_t	 RANAP_IMSI_t;
 
 /* Implementation */
 extern asn_TYPE_descriptor_t asn_DEF_RANAP_IMSI;