Documentation/device_model: Fix bex_misc probe test instruction

Even though the probe from 'bex_misc' fails, the device is added.
Therefore, following the test instruction of creating device of name
'test' again fails, as the same name device is already created.  This
commit updates the instruction to use different name, 'test2' for second
try.

Signed-off-by: SeongJae Park <sj38.park@gmail.com>

Author: sjp38

Documentation/teaching/labs/device_model.rst

@@ -1259,10 +1259,10 @@ defined misc device in ``bex_misc_probe`` and deregister it in
 
 Create a new device with the name "test", type "misc" and version 2
 and observe that the probe fails. Create a new device with the name
-"test", type "misc" and version 1 and observe that the probe is
+"test2", type "misc" and version 1 and observe that the probe is
 successful.
 
-Inspect ``/sys/bus/bex/devices/test`` and observe that we have a new
+Inspect ``/sys/bus/bex/devices/test2`` and observe that we have a new
 entry. Identify the major and minor for the misc device, create a
 character device file and try to read and write from the misc device
 buffer.