staging: lustre: lnet: add static to libcfs_dev declaration

Add a static prefix to the declaration for libcfs_dev. This would fix
the following sparse warning:

drivers/staging/lustre/lnet/libcfs/module.c:317:19: warning: symbol
'libcfs_dev' was not declared. Should it be static?
Signed-off-by: NJustin Skists <justin.skists@juzza.co.uk>
Reviewed-by: NNeilBrown <neilb@suse.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lnet/libcfs/module.c

@@ -314,7 +314,7 @@ static const struct file_operations libcfs_fops = {
 	.unlocked_ioctl	= libcfs_psdev_ioctl,
 };
 
-struct miscdevice libcfs_dev = {
+static struct miscdevice libcfs_dev = {
 	.minor = MISC_DYNAMIC_MINOR,
 	.name = "lnet",
 	.fops = &libcfs_fops,