avr32: At32ap: pio fix typo "))" on gpio_irq_unmask prototype

introduce in commit d75f1bfd

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Patrice Vilchez <patrice.vilchez@atmel.com>
Signed-off-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>