drm/tests: Add back seed value information

As reported by Michał, the drm_mm and drm_buddy unit tests lost the
printk with seed value after they were refactored into KUnit.

Add kunit_info with seed value information to assure reproducibility.

Reported-by: Michał Winiarski <michal.winiarski@intel.com>
Signed-off-by: Arthur Grillo <arthurgrillo@riseup.net>
Signed-off-by: Maíra Canal <mairacanal@riseup.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20221028221755.340487-1-arthurgrillo@riseup.net