staging: dwc2: do not use IRQF_DISABLED

This flag is a deprecated NOOP, interrupt handlers are always run
with interupts disabled.

See commit 6932bf37 (genirq: Remove IRQF_DISABLED from core code), and
include/linux/interrupt.h:

	 * IRQF_DISABLED - keep irqs disabled when calling the action handler.
	 *                 DEPRECATED. This flag is a NOOP and scheduled to be removed

Signed-off-by: Matthijs Kooijman <matthijs@stdin.nl>
Acked-by: Paul Zimmerman <paulz@synopsys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>