USB: EHCI: Don't use NO_IRQ in xilinx ehci driver

Drivers shouldn't use NO_IRQ. This driver is used
by Microblaze and PPC. PPC defines NO_IRQ as 0
and Microblaze has removed it.

Signed-off-by: Michal Simek <monstr@monstr.eu>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
CC: Greg Kroah-Hartman <gregkh@suse.de>
CC: Grant Likely <grant.likely@secretlab.ca>
CC: linux-usb@vger.kernel.org
CC: devicetree-discuss@lists.ozlabs.org