drm/vc4: plane: Remove subpixel positioning check

[ Upstream commit 517db1ab1566dba3093dbdb8de4263ba4aa66416 ]

There is little harm in ignoring fractional coordinates
(they just get truncated).

Without this:
modetest -M vc4 -F tiles,gradient -s 32:1920x1080-60 -P89@74:1920x1080*.1.1@XR24

is rejected. We have the same issue in Kodi when trying to
use zoom options on video.

Note: even if all coordinates are fully integer. e.g.
src:[0,0,1920,1080] dest:[-10,-10,1940,1100]

it will still get rejected as drm_atomic_helper_check_plane_state
uses drm_rect_clip_scaled which transforms this to fractional src coords

Fixes: 21af94cf ("drm/vc4: Add support for scaling of display planes.")
Signed-off-by: Dom Cobley <popcornmix@gmail.com>
Link: https://lore.kernel.org/r/20220613144800.326124-5-maxime@cerno.tech


Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Signed-off-by: Sasha Levin <sashal@kernel.org>