USB: output an error message when the pipe type doesn't match the endpoint type

Commit f661c6f8 adds a check of the pipe type if
CONFIG_USB_DEBUG is enabled, but it doesn't output anything if this scenario
occurs.

Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>