ipmi: do not omit lun in BMC addresses

Some systems put sensors on non-0 lun, so we should not omit it.  This
was the only difference with the Linux driver, where DIMM sensors could
be queried, but not on FreeBSD.

See this report[1] on the FreeBSD forums:
https://forums.freebsd.org/threads/freebsd-cannot-get-dimm-temperature-sensor-value.85166/

Reviewed by:	philip
Tested by:	Andrey Lanin[1]
MFC after:	1 week
Differential Revision: https://reviews.freebsd.org/D35612

sys/dev/ipmi/ipmi.c

@@ -309,9 +309,12 @@ ipmi_ioctl(struct cdev *cdev, u_long cmd, caddr_t data,
 			return (error);
 
 		if (addr.addr_type == IPMI_SYSTEM_INTERFACE_ADDR_TYPE) {
+			struct ipmi_system_interface_addr *saddr =
+			    (struct ipmi_system_interface_addr *)&addr;
+
 			kreq = ipmi_alloc_request(dev, req->msgid,
-			    IPMI_ADDR(req->msg.netfn, 0), req->msg.cmd,
-			    req->msg.data_len, IPMI_MAX_RX);
+			    IPMI_ADDR(req->msg.netfn, saddr->lun & 0x3),
+			    req->msg.cmd, req->msg.data_len, IPMI_MAX_RX);
 			error = copyin(req->msg.data, kreq->ir_request,
 			    req->msg.data_len);
 			if (error) {