Unbreak RaspberryPi 2 boot after r332839

r332839 changed number of cells per interrupt for local_intc from 1 to 2
to pass type of IRQ. Driver expected only 1 cell so after r332839
all interrupt children of local_intc failed to allocate IRQ resource.

Fix this regression by relaxing check for number of cells in interrupt
property to be either 1 or 2.

PR: 227904