drm/tests: Add calls to drm_fb_blit() on supported format conversion tests

Add a call to drm_fb_blit() on existing format conversion tests that
has support.

Signed-off-by: Arthur Grillo <arthurgrillo@riseup.net>
Reviewed-by: Maíra Canal <mairacanal@riseup.net>
Signed-off-by: Maíra Canal <mairacanal@riseup.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20230918-final-gsoc-v3-1-b999c042a4cc@riseup.net