ARM: bcm283x: Add missing interrupt for RNG block

This patch adds the missing interrupt property to the RNG block
of BCM283x.

Link: https://github.com/raspberrypi/linux/issues/2195


CC: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>