Detected by valgrind. Leak introduced in commit e9bd9a08:

* tools/virsh.c: fix memory leak on cmdBlkdeviotune.

* how to reproduce?
  % valgrind -v --leak-check=full virsh blkdeviotune <domain name> <block device>

* actual valgrind result:

==12759== 576 bytes in 1 blocks are definitely lost in loss record 18 of 29
==12759==    at 0x4A04A28: calloc (vg_replace_malloc.c:467)
==12759==    by 0x42134E: _vshCalloc.clone.2 (virsh.c:422)
==12759==    by 0x4217CB: cmdBlkdeviotune (virsh.c:6364)
==12759==    by 0x4136A2: vshCommandRun (virsh.c:16363)
==12759==    by 0x4253FB: main (virsh.c:17865)
==12759==
==12759== LEAK SUMMARY:
==12759==    definitely lost: 576 bytes in 1 blocks
==12759==    indirectly lost: 0 bytes in 0 blocks
==12759==      possibly lost: 0 bytes in 0 blocks
==12759==    still reachable: 126,964 bytes in 1,342 blocks
==12759==         suppressed: 0 bytes in 0 blocks
Signed-off-by: NAlex Jia <ajia@redhat.com>