irqchip: sirf: fix one minor checkpatch issue

fix "line line over 80 characters" for the below:
static int __init sirfsoc_irq_init(struct device_node *np, struct device_node *parent)

the users of the codes - key customers really care about that.

Signed-off-by: Bin Shi <Bin.Shi@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>