mmc: cd-gpio: pass IRQF_ONESHOT to request_threaded_irq()

Fix a boot regression on Mackerel boards with sh_mobile_sdhi
in existing kernels causing:

genirq: Threaded irq requested with handler=NULL and !ONESHOT for irq XXX

caused by 1c6c6952 (genirq: Reject bogus threaded irq requests).

This is backported from Guennadi's patch:
"mmc: extend and rename cd-gpio helpers to handle more slot GPIO functions"

Reported-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Chris Ball <cjb@laptop.org>