sh: landisk updates.

Updates for the landisk board:

	- The push_switch framework was used.
	- landisk_pwb.c was divided into psw.c and gio.c.
	- pata_platform was supported in USL-5P.
	- irq.c was rewritten.
	- io.c was replaced with generic I/O routines.

Signed-off-by: kogiidena <kogiidena@eggplant.ddo.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>