usb: chipidea: trim include list in udc code

Some headers included in udc core code are not actually needed, remove
them and add irqreturn.h, which was implicitly included via irq.h.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>