gigaset: fix Oops on module unload regression

The card state mutex was only initialized when a device was connected,
but used during unload unconditionally, leading to an Oops if a driver
was loaded and unloaded again without ever connecting a device.

Fix this by initializing the mutex as soon as the structure is allocated.
Also add a missing mutex unlock revealed in the same execution path.

This fixes a possible Oops in 2.6.25-rc that was introduced by commit
e468c04894f36045cf93d1384183a461014b6840 ("Gigaset: permit module
unload").

Thanks to Roland Kletzing for reporting this problem.

Signed-off-by: Tilman Schmidt <[e-mail]>
Tested-by: Roland Kletzing <[e-mail]>
Cc: Hansjoerg Lipp <[e-mail]>
Cc: Karsten Keil <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/isdn/gigaset/common.c

···
 		err("maximum number of devices exceeded");
 		return NULL;
 	}
-	mutex_init(&cs->mutex);
 
 	gig_dbg(DEBUG_INIT, "allocating bcs[0..%d]", channels - 1);
 	cs->bcs = kmalloc(channels * sizeof(struct bc_state), GFP_KERNEL);
···
 {
 	mutex_lock(&cs->mutex);
 
-	if (!(cs->flags & VALID_MINOR))
+	if (!(cs->flags & VALID_MINOR)) {
+		mutex_unlock(&cs->mutex);
 		return -1;
+	}
 
 	cs->waiting = 1;
 
···
 		drv->cs[i].driver = drv;
 		drv->cs[i].ops = drv->ops;
 		drv->cs[i].minor_index = i;
+		mutex_init(&drv->cs[i].mutex);
 	}
 
 	gigaset_if_initdriver(drv, procname, devname);