Driver core: convert tty core to use struct device

Converts from using struct "class_device" to "struct device" making
everything show up properly in /sys/devices/ with symlinks from the
/sys/class directory.

Also fixes up the isdn drivers that were putting something in the class
device's directory.

Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/isdn/gigaset/common.c b/drivers/isdn/gigaset/common.c
index 5800beee..defd5743 100644
--- a/drivers/isdn/gigaset/common.c
+++ b/drivers/isdn/gigaset/common.c
@@ -702,7 +702,7 @@
 	cs->open_count = 0;
 	cs->dev = NULL;
 	cs->tty = NULL;
-	cs->class = NULL;
+	cs->tty_dev = NULL;
 	cs->cidmode = cidmode != 0;
 
 	//if(onechannel) { //FIXME