arm64: dts: renesas: white-hawk-cpu-common: Add pin control for DSI-eDP IRQ

arm64: dts: renesas: white-hawk-cpu-common: Add pin control for DSI-eDP IRQ

When the DSI to eDP bridge was added, pin control for the IRQ pin was
left out, because the pin controller did not support INTC-EX pins yet.

Commit 10544ec1b3436037 ("pinctrl: renesas: r8a779g0: Add INTC-EX
pins, groups, and function") added support for these pins, so add the
missing pin control description.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/89bab2008891be1f003a3c0dbcdf36af3b98da70.1729240573.git.geert+renesas@glider.be