drm/meson: Add HDMI 1.4 4k modes

Add the timings for the HDMI 1.4 4K modes support :
- 3840x2160@30
- 3840x2160@25
- 3840x2160@24

Since the 297000Hz pixel clock is already managed and the modes are
compatible with the HDMI 1.4 current HDMI PHY+Controller support, only
the missing timings values needs to be added.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Maxime Jourdan <mjourdan@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1541496909-19625-1-git-send-email-narmstrong@baylibre.com