genirq: Fix typo in comment of IRQD_MOVE_PCNTXT

Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Dou Liyang <douliyangs@gmail.com>
Cc: Julien Thierry <julien.thierry@arm.com>
Link: https://lkml.kernel.org/r/20190318065123.11862-1-peterx@redhat.com