stdio/device: rework function naming convention

So far the console API uses the following naming convention:

	======Extract======
	typedef struct device_t;

	int	device_register (device_t * dev);
	int	devices_init (void);
	int	device_deregister(char *devname);
	struct list_head* device_get_list(void);
	device_t* device_get_by_name(char* name);
	device_t* device_clone(device_t *dev);
	=======

which is too generic and confusing.

Instead of using device_XX and device_t we change this
into stdio_XX and stdio_dev

This will also allow to add later a generic device mechanism in order
to have support for multiple devices and driver instances.

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

Edited commit message.

Signed-off-by: Wolfgang Denk <wd@denx.de>