pcmcia/vrc4171: Add missing spinlock init

It doesn't seem this spinlock was properly initialized. This bug was
introduced by commit 7a410e8d.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>