make "PLL mode" setting actually work rather than segfault

diff --git a/src/abis_nm.c b/src/abis_nm.c
index 3cbfd84..6e0f5bad 100644
--- a/src/abis_nm.c
+++ b/src/abis_nm.c
@@ -1738,13 +1738,19 @@
 {
 	struct abis_om_hdr *oh;
 	struct msgb *msg;
+	u_int8_t tlv_value;
 	
 	msg = nm_msgb_alloc();
 	oh = (struct abis_om_hdr *) msgb_put(msg, ABIS_OM_FOM_HDR_SIZE);
 	fill_om_fom_hdr(oh, 3, NM_MT_BS11_SET_ATTR, NM_OC_BS11,
 			BS11_OBJ_LI, 0x00, 0x00);
-	msgb_tlv_put(msg, NM_ATT_BS11_PLL_MODE, 1,
-		     locked ? BS11_LI_PLL_LOCKED : BS11_LI_PLL_STANDALONE);
+
+	if (locked)
+		tlv_value = BS11_LI_PLL_LOCKED;
+	else
+		tlv_value = BS11_LI_PLL_STANDALONE;
+	
+	msgb_tlv_put(msg, NM_ATT_BS11_PLL_MODE, 1, &tlv_value);
 	
 	return abis_nm_sendmsg(bts, msg);
 }