Still use IRQF_SHARED for the usb interrupt, but:
* The IRQ handler in ehci-mxs, that's set in hc_driver.irq would be
always
returning IRQ_NONE.
* The IRQ handler in imx-otg would call the callback registered via
imx_otg_set_irq_handler() only if the port was actually in host mode

The interrupt which is registered by hcd core is usb_hcd_irq, it will call
ehci_irq. The hc_driver.irq is included in usb_hcd_irq.