pcmcia: use mutex for dynid lock

Even though we weren't calling a blocking function within the dynid
spinlock, we do not need a spinlock here but can and should be using
a mutex.

Reported-by: Jiri Slaby <jirislaby@gmail.com>
Tested-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>

include/pcmcia/ds.h

@@ -40,7 +40,7 @@ struct net_device;
  * Documentation/pcmcia/driver.txt for details.
 */
 struct pcmcia_dynids {
-	spinlock_t		lock;
+	struct mutex		lock;
 	struct list_head	list;
 };