DM devices are not being created for the Luns with minor numbers greater than
256 when mpath_prio_alua is used as path_prio_callout routine.

How reproducible:
=======================
Always

Steps to Reproduce:
=======================
1.      present larger set of LUNs (with more than 2 HBAs in the host and
having exposed paths from each HBA for the Lun) from HSV111 array to the host
2.      Following are the Parameters in /etc/mutilapth.conf for HSV210 Devices
        device {
                vendor                  "HP*"
                product                 "HSV111"
                path_grouping_policy    group_by_prio
                prio_callout            "/sbin/mpath_prio_alua %d"
                getuid_callout          "/sbin/scsi_id -g -u -s /block/%n"
                path_checker            tur
                path_selector           "round-robin 0"
                hardware_handler        "0"
                failback                immediate
                rr_weight               priorities
                no_path_retry           60
                rr_min_io               1000
                product_blacklist       LUN_Z
        } 
4.      Reboot the system

Actual Results:
=========================
DM devices are not created for HSV111 Luns for the paths with dev_t minor
numbers greater than 256


Initial investigation and analysis:
====================================

The issue seems to be b'cos of mpath_prio_alua and its argument as %d. 
With "multipath -v3" output, the messages shows that, "mpath_prio_alua" with "%
d" as argument return -1 for the devices with dev_t minor numbers greater than 
256.
For Example, the devices with dev_t maj:min numbers as 71:256, 68:384 reports
these error, and the multipath devices are not getting vreated for those Luns. 

But, "mpath_prio_alua" with "%n" for the same devices returns the valid
priority for those devices and the multipath devices are succesfully created.


"mpath_prio_alua %d" and "mpath_prio_alua %n" behave differently with the later
one works well with all devices and the earlier one doesnt work with the
devices having minor number greater than 256.