scripts/coccinelle/misc/irqf_oneshot.cocci: Fix grammar

Correct form is 'always requested'.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Michal Marek <mmarek@suse.cz>