drm/ttm/tests: Require MMU when testing

Satisfy MMU dependency when testing TTM with KUnit. This fixes
compilation errors on platforms that don't select this option
by default.
Signed-off-by: Karolina Stolarek <karolina.stolarek@intel.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202308110133.f0lhFwMV-lkp@intel.com/
Closes: https://lore.kernel.org/oe-kbuild-all/202308111032.enU8IisR-lkp@intel.com/Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230811113649.697886-1-karolina.stolarek@intel.comSigned-off-by: Christian König <christian.koenig@amd.com>

drivers/gpu/drm/Kconfig

@@ -198,7 +198,7 @@ config DRM_TTM
 config DRM_TTM_KUNIT_TEST
         tristate "KUnit tests for TTM" if !KUNIT_ALL_TESTS
         default n
-        depends on DRM && KUNIT
+        depends on DRM && KUNIT && MMU
         select DRM_TTM
         select DRM_EXPORT_FOR_TESTS if m
         select DRM_KUNIT_TEST_HELPERS