btrfs: sysfs: unexport btrfs_raid_ktype

The last non-sysfs usage of btrfs_raid_ktype has been moved to a private
helper in previous patch so the variable can be made static.
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/sysfs.c

@@ -336,7 +336,7 @@ static void release_raid_kobj(struct kobject *kobj)
 	kfree(to_raid_kobj(kobj));
 }
 
-struct kobj_type btrfs_raid_ktype = {
+static struct kobj_type btrfs_raid_ktype = {
 	.sysfs_ops = &kobj_sysfs_ops,
 	.release = release_raid_kobj,
 	.default_groups = raid_groups,

fs/btrfs/sysfs.h

@@ -80,7 +80,6 @@ attr_to_btrfs_feature_attr(struct attribute *attr)
 char *btrfs_printable_features(enum btrfs_feature_set set, u64 flags);
 extern const char * const btrfs_feature_set_names[FEAT_MAX];
 extern struct kobj_type space_info_ktype;
-extern struct kobj_type btrfs_raid_ktype;
 int btrfs_sysfs_add_device_link(struct btrfs_fs_devices *fs_devices,
 		struct btrfs_device *one_device);
 int btrfs_sysfs_rm_device_link(struct btrfs_fs_devices *fs_devices,