Fix MIB encoding in F1SetupRequest: use encode_MIB_NR_setup instead of encode_MIB_NR

- The DU was using encode_MIB_NR() while constructing the GNB-DU System Information for the F1SetupRequest.
- encode_MIB_NR() encodes a full NR_BCCH_BCH_Message_t, causing the MIB to be wrapped in a BCH container.
- This results in incorrect MIB values in the F1SetupRequest PCAP (e.g., wrong systemFrameNumber, SCS, DMRS position, cellBarred).
- According to 3GPP TS 38.473, the MIB carried in F1AP must be encoded as a raw NR_MIB_t.
- The correct function encode_MIB_NR_setup() encodes MIB in the required format but was not used.
- This patch replaces encode_MIB_NR() with encode_MIB_NR_setup() to ensure correct and standards-compliant MIB encoding in the F1SetupRequest.

Closes issue #1034.

openair2/GNB_APP/gnb_config.c

@@ -1127,7 +1127,7 @@ f1ap_gnb_du_system_info_t *get_sys_info(NR_BCCH_BCH_Message_t *mib, const NR_BCC
 
   sys_info->mib = calloc_or_fail(buf_len, sizeof(*sys_info->mib));
   DevAssert(mib != NULL);
-  sys_info->mib_length = encode_MIB_NR(mib, 0, sys_info->mib, buf_len);
+  sys_info->mib_length = encode_MIB_NR_setup(mib->message.choice.mib, 0, sys_info->mib, buf_len);
   DevAssert(sys_info->mib_length == buf_len);
 
   DevAssert(sib1 != NULL);