dahdi: Initialize the channels cdev structure.

This is necessary to prevent a crash when opening files by the new
device files, which do not have a valid file_operations structure.
This fixes a problem does not exist in any releases of DAHDI.

Since none of the existing tools or applications open files from the
new location of /dev/dahdi/channels/<span>/<offset>, this wasn't
seen until just recently.

Reported-by: Ted Gerold <ted@twg.org>
Signed-off-by: Shaun Ruffell <sruffell@digium.com>

drivers/dahdi/dahdi-sysfs-chan.c

@@ -463,6 +463,7 @@ int __init dahdi_sysfs_chan_init(const struct file_operations *fops)
 		goto cleanup;
 	}
 	dahdi_dbg(DEVICES, "adding channels cdev\n");
+	cdev_init(&dahdi_channels_cdev, fops);
 	res = cdev_add(&dahdi_channels_cdev, dahdi_channels_devt,
 		DAHDI_MAX_CHANNELS);
 	if (res) {