Alchemy Semi Au1000 pcmcia driver: convert pcmcia_sockets_lock in a mutex

Alchemy Semi Au1000 pcmcia driver: The semaphore pcmcia_sockets_lock
is used as a mutex, convert it to the mutex API

(akpm: make it static too)

Signed-off-by: Matthias Kaehlcke <matthias@kaehlcke.net>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>