s390/cio: wait_cons_dev don't use static variable

wait_cons_dev is used to busy wait for an interrupt on the console
ccw device. Stop using the static console_subchannel and add a
parameter to this function to specify on which ccw device/subchannel
we have to do the polling.

While at it rename the function to ccw_device_wait_idle and
move it to device.c

Reviewed-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/char/con3215.c b/drivers/s390/char/con3215.c
index 7b00fa6..0d79eec 100644
--- a/drivers/s390/char/con3215.c
+++ b/drivers/s390/char/con3215.c
@@ -502,7 +502,7 @@
 		raw3215_try_io(raw);
 		raw->flags &= ~RAW3215_FLUSHING;
 #ifdef CONFIG_TN3215_CONSOLE
-		wait_cons_dev();
+		ccw_device_wait_idle(raw->cdev);
 #endif
 		/* Enough room freed up ? */
 		if (RAW3215_BUFFER_SIZE - raw->count >= length)