tests: fix modules-test 'duplicate test case' error

tests: fix modules-test 'duplicate test case' error

./configure --enable-sdl --audio-drv-list=sdl --enable-modules

Will generate two identical test names: /$arch/module/load/sdl
Which generates an error like:

(tests/modules-test:23814): GLib-ERROR **: 18:23:06.359: duplicate test case path: /aarch64//module/load/sdl

Add the subsystem prefix in the name as well, so instead we get:

/$arch/module/load/audio-sdl
/$arch/module/load/ui-sdl

Signed-off-by: Cole Robinson <crobinso@redhat.com>
Message-Id: <d64c9aa098cc6e5c0b638438c4959eddfa7e24e2.1573679311.git.crobinso@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
(cherry picked from commit eca3a945234a5f0a499860dd11df64b5f1a2e0a5)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>