medial: use irqsave() in URB completion + usb_fill_int_urb

[Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>]

This series is mostly about using _irqsave() primitives in the
completion callback in order to get rid of local_irq_save() in
__usb_hcd_giveback_urb(). While at it, I also tried to move drivers to
use usb_fill_int_urb() otherwise it is hard find users of a certain API.
 
Sebastian