arm64: dts: renesas: falcon-cpu: Use INTC_EX for SN65DSI86

arm64: dts: renesas: falcon-cpu: Use INTC_EX for SN65DSI86

The INTC block is a better choice for handling the interrupts on the V3U
as the INTC will always be powered, while the GPIO block may be
de-clocked if not in use. Further more, it may be likely to have a lower
power consumption as it does not need to drive the pins.

Switch the interrupt parent and interrupts definition from gpio1 to
irq0 on intc_ex, and configure the PFC accordingly.

Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Link: https://lore.kernel.org/r/20220309190631.1576372-1-kieran.bingham+renesas@ideasonboard.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>