MIPS: bcm63xx: Use irq_set_handler_locked()

Use irq_set_handler_locked() as it avoids a redundant lookup of the
irq descriptor.

Search and replacement was done with coccinelle.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: LKML <linux-kernel@vger.kernel.org>
Patchwork: https://patchwork.linux-mips.org/patch/10701/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>