Fix inconsistency in {max,min}_interval naming

In some places this field was named conn_{max,min}_interval, removing
"conn_" so it is consistent with the rest of the code.
diff --git a/lib/hci.h b/lib/hci.h
index aea423f..7e3e328 100644
--- a/lib/hci.h
+++ b/lib/hci.h
@@ -1392,8 +1392,8 @@
 #define OCF_LE_CONN_UPDATE			0x0013
 typedef struct {
 	uint16_t	handle;
-	uint16_t	conn_min_interval;
-	uint16_t	conn_max_interval;
+	uint16_t	min_interval;
+	uint16_t	max_interval;
 	uint16_t	latency;
 	uint16_t	supervision_timeout;
 	uint16_t	min_ce_length;