drm/bridge: anx7625: Use uint8 for lane-swing arrays

As defined in the anx7625 dt-binding, the analogix,lane0-swing and
analogix,lane1-swing properties are uint8 arrays. Yet, the driver was
reading the array as if it were of uint32 and masking to 8-bit before
writing to the registers. This means that a devicetree written in
accordance to the dt-binding would have its values incorrectly parsed.

Fix the issue by reading the array as uint8 and storing them as uint8
internally, so that we can also drop the masking when writing the
registers.

Fixes: fd0310b6

 ("drm/bridge: anx7625: add MIPI DPI input feature")
Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220408013034.673418-1-nfraprado@collabora.com