ubifs: Use correct config name for encryption

CONFIG_UBIFS_FS_ENCRYPTION is gone, fscrypt is now
controlled via CONFIG_FS_ENCRYPTION.
This problem slipped into the tree because of a mis-merge on
my side.
Reported-by: Eric Biggers <ebiggers@kernel.org>
Fixes: eea2c05d ("ubifs: Remove #ifdef around CONFIG_FS_ENCRYPTION")
Signed-off-by: Richard Weinberger <richard@nod.at>

fs/ubifs/sb.c

@@ -748,7 +748,7 @@ int ubifs_read_superblock(struct ubifs_info *c)
 		goto out;
 	}
 
-	if (!IS_ENABLED(CONFIG_UBIFS_FS_ENCRYPTION) && c->encrypted) {
+	if (!IS_ENABLED(CONFIG_FS_ENCRYPTION) && c->encrypted) {
 		ubifs_err(c, "file system contains encrypted files but UBIFS"
 			     " was built without crypto support.");
 		err = -EINVAL;
@@ -941,7 +941,7 @@ int ubifs_enable_encryption(struct ubifs_info *c)
 	int err;
 	struct ubifs_sb_node *sup = c->sup_node;
 
-	if (!IS_ENABLED(CONFIG_UBIFS_FS_ENCRYPTION))
+	if (!IS_ENABLED(CONFIG_FS_ENCRYPTION))
 		return -EOPNOTSUPP;
 
 	if (c->encrypted)