USB: hcd.h : Removed an unnecessary function prototype usb_find_interface_driver()

This function is used to call in early version of linux kernel in order
to find out the interface used by a usb device. But now it's use is
completely abolished. So,it would be relevant to remove this obselete
function from kernel mainline.

Signed-off-by: Abhishek Bist <ishubist@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>