drm/panel: simple: Convert Innolux G121X1-L03 to display_timing

Use display_timing instead of drm_display_mode to define a range of
possible display timings supported by this panel. This makes the panel
support more flexible and improves compatibility. No functional change
is expected.

The settings are picked from documentation [1] section 6.1 INPUT SIGNAL
TIMING SPECIFICATIONS.

[1] https://www.distec.de/fileadmin/pdf/produkte/TFT-Displays/Innolux/G121X1-L03_Datasheet.pdf



Signed-off-by: Marek Vasut <marex@denx.de>
Acked-by: Jessica Zhang <quic_jesszhan@quicinc.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240328102746.17868-3-marex@denx.de