drm: lcdif: Use adjusted_mode .clock instead of .crtc_clock

In case an upstream bridge modified the required clock frequency
in its .atomic_check callback by setting adjusted_mode.clock ,
make sure that clock frequency is generated by the LCDIFv3 block.

This is useful e.g. when LCDIFv3 feeds DSIM which feeds TC358767
with (e)DP output, where the TC358767 expects precise timing on
its input side, the precise timing must be generated by the LCDIF.

Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240531202813.277109-1-marex@denx.de