media: verisilicon: Do not enable G2 postproc downscale if source is narrower than destination

In case of encoded input VP9 data width that is not multiple of macroblock
size, which is 16 (e.g. 1080x1920 frames, where 1080 is multiple of 8), the
width is padded to be a multiple of macroblock size (for 1080x1920 frames,
that is 1088x1920).

The hantro_postproc_g2_enable() checks whether the encoded data width is
equal to decoded frame width, and if not, enables down-scale mode. For a
frame where input is 1080x1920 and output is 1088x1920, this is incorrect
as no down-scale happens, the frame is only padded. Enabling the down-scale
mode in this case results in corrupted frames.

Fix this by adjusting the check to test whether encoded data width is
greater than decoded frame width, and only in that case enable the
down-scale mode.

To generate input test data to trigger this bug, use e.g.:
$ gst-launch-1.0 videotestsrc ! video/x-raw,width=272,height=256,format=I420 ! \
                 vp9enc ! matroskamux ! filesink location=/tmp/test.vp9
To trigger the bug upon decoding (note that the NV12 must be forced, as
that assures the output data would pass the G2 postproc):
$ gst-launch-1.0 filesrc location=/tmp/test.vp9 ! matroskademux ! vp9parse ! \
                 v4l2slvp9dec ! video/x-raw,format=NV12 ! videoconvert ! fbdevsink

Fixes: 79c987de ("media: hantro: Use post processor scaling capacities")
Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>