bcachefs: acl: Uninitialized variable in bch2_acl_chmod()

The clean up code at the end of the function uses "acl" so it needs
to be initialized to NULL.

Fixes: 53306e096d91 ("bcachefs: Always check for transaction restarts")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/acl.c

@@ -417,7 +417,7 @@ int bch2_acl_chmod(struct btree_trans *trans, subvol_inum inum,
 	struct btree_iter iter;
 	struct bkey_s_c_xattr xattr;
 	struct bkey_i_xattr *new;
-	struct posix_acl *acl;
+	struct posix_acl *acl = NULL;
 	struct bkey_s_c k;
 	int ret;