[gsm0408] Add parameter to gsm48_send_rr_ciph_mode for controling the response

This parameter controls if the response should include the
IMEISV or not. This will be set by the MSC and this is why
this parameter was added.
diff --git a/openbsc/src/gsm_04_08_utils.c b/openbsc/src/gsm_04_08_utils.c
index 88edc7d..ef9e59c 100644
--- a/openbsc/src/gsm_04_08_utils.c
+++ b/openbsc/src/gsm_04_08_utils.c
@@ -459,7 +459,7 @@
 }
 
 /* Chapter 9.1.9: Ciphering Mode Command */
-int gsm48_send_rr_ciph_mode(struct gsm_lchan *lchan)
+int gsm48_send_rr_ciph_mode(struct gsm_lchan *lchan, int want_imeisv)
 {
 	struct msgb *msg = gsm48_msgb_alloc();
 	struct gsm48_hdr *gh;
@@ -477,7 +477,7 @@
 	gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh) + 1);
 	gh->proto_discr = GSM48_PDISC_RR;
 	gh->msg_type = GSM48_MT_RR_CIPH_M_CMD;
-	gh->data[0] = 0x10 | (ciph_mod_set & 0xf);
+	gh->data[0] = (want_imeisv & 0x1) << 4 | (ciph_mod_set & 0xf);
 
 	return rsl_encryption_cmd(msg);
 }