omap: mailbox: remove unecessary fields

struct omap_mbox {

	char			*name;

	unsigned int		irq;

	struct omap_mbox_queue	*txq, *rxq;

	struct omap_mbox_ops	*ops;

	mbox_msg_t		seq_snd, seq_rcv;

	struct device		*dev;

	struct omap_mbox	*next;

	void			*priv;

	void			(*err_notify)(void);

};

int omap_mbox_msg_send(struct omap_mbox *, mbox_msg_t msg);