drm/v3d: Update top-level kerneldoc for the addition of TFU.

Signed-off-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20190207201001.5730-1-eric@anholt.net


Reviewed-by: Thomas Spurden <thomas.spurden@broadcom.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>