usb: move USB_REQ_{GET,SET}_CONFIGURATION handling to common code

This patch adds fields to the USBDevice struct for the current
speed (hard-wired to full speed for now) and current device
configuration.  Also a init function is added which inializes
these fields.  This allows USB_REQ_{GET,SET}_CONFIGURATION
handling to be moved to common code.

For most drivers the conversion is trivial ad they support a single
configuration only anyway.  One exception is bluetooth where some
device-specific setup code runs after get/set configuration.  The
other is usb-net which actually has two configurations so the
the code to check for the active configuration has been adapted.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
