staging: dgnc: rename dgnc_finalize_board_init() to dgnc_request_irq()

The dgnc_finalize_board_init() function has only job for
requesting the IRQ. It should be renamed to dgnc_request_irq()

Signed-off-by: Daeseok Youn <daeseok.youn@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>