dts: riscv32-fe310: add missing clint properties
dts: riscv32-fe310: add missing clint properties

RISC-V clint is an interrupt controller but it has no required
properties (#interrupt-cells and interrupt-controller).
This patch just adds missing properties.

Signed-off-by: Katsuhiro Suzuki <bf35892f8952532211147f11fbacf7cdaff1e86f@katsuster.net>

zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,Vudentz/zephyr,nashif/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,finikorg/zephyr,nashif/zephyr,nashif/zephyr,galak/zephyr,Vudentz/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,finikorg/zephyr,Vudentz/zephyr,galak/zephyr,Vudentz/zephyr