avocado_qemu: fix inheritance order on LinuxTest class

Class hierarchy on Python is defined from right to left. Although the
current code is not harmful, let's fix it to avoid problems in the future.

Signed-off-by: Willian Rampazzo <willianr@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210920204932.94132-7-willianr@redhat.com>

tests/acceptance/avocado_qemu/__init__.py

@@ -424,7 +424,7 @@ def default_kernel_params(self):
         return self._info.get('kernel_params', None)
 
 
-class LinuxTest(Test, LinuxSSHMixIn):
+class LinuxTest(LinuxSSHMixIn, Test):
     """Facilitates having a cloud-image Linux based available.
 
     For tests that indend to interact with guests, this is a better choice