arm64: dts: renesas: beacon-renesom: Use interrupts-extended for touchscreen

Use the more concise interrupts-extended property to fully describe the
interrupt.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/c1ee39ab194f1d04d56af6804fd9e7632710154f.1728045620.git.geert+renesas@glider.be