drm/meson: vclk: fix calculation of 59.94 fractional rates

Playing 4K media with 59.94 fractional rate (typically VP9) causes the screen to lose
sync with the following error reported in the system log:

[   89.610280] Fatal Error, invalid HDMI vclk freq 593406

Modetest shows the following:

3840x2160 59.94 3840 4016 4104 4400 2160 2168 2178 2250 593407 flags: xxxx, xxxx,
drm calculated value -------------------------------------^

Change the fractional rate calculation to stop DIV_ROUND_CLOSEST rounding down which
results in vclk freq failing to match correctly.

Fixes: e5fab2ec ("drm/meson: vclk: add support for YUV420 setup")
Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20240109230704.4120561-1-christianshewitt@gmail.com


Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240109230704.4120561-1-christianshewitt@gmail.com