mdadm/tests: 07autoassemble

mdadm/tests: 07autoassemble

This test is used to test stacked array auto assemble.

There are two different cases depends on if array is foreign or not.
If the array is foreign, the stacked array (md0 is on md1 and md2)
can't be assembled with name md0. Because udev rule will run when md1
and md2 are assembled and mdadm -I doesn't specify homehost. So it
will treat stacked array (md0) as foreign array and choose md127 as
the device node name (/dev/md127)

Add the case that stacked array is local.

Signed-off-by: Xiao Ni <xni@redhat.com>
Signed-off-by: Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>