drm/meson: venc: add support for HDMI DMT modes up to 3840x2160

drm/meson: venc: add support for HDMI DMT modes up to 3840x2160

Commit 5d0bfe448481 ("drm/meson: Add HDMI 1.4 4k modes") added support
for HDMI 1.4 4k modes, which is what TVs need. For computer monitors
the code is using the DMT code-path, which ends up in
meson_venc_hdmi_supported_mode(), which does not allow the 4k modes yet.

The datasheet for all supported SoCs mentions "4Kx2K@60". It's not
clear whether "4K" here means 3840 or 4096 pixels.

Allow resolutions up to 3840x2160 pixels (including middle steps, such
as WQHD at 2560x1440 pixels) so they can be used with computer monitors
(using the DMT code-path in the driver).

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Acked-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patch.msgid.link/20251108134236.1299630-1-martin.blumenstingl@googlemail.com