The USB core is changing the way interfaces and altsettings are stored.
They are no longer required to be in numerical order, and as a result,
simply indexing the interface and altsetting arrays won't work as
expected.

This patch for the st5481 takes these changes into account.  A simpler
approach would be to store a pointer to the struct usb_host_interface
rather than look it up repeatedly, but I'm not very familiar with this
driver and didn't want to attempt such an alteration.