gpio: vf610: 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: Julia Lawall <julia.lawall@lip6.fr>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: linux-gpio@vger.kernel.org