fuse: fallocate: fix return with locked inode

commit 35d6fcbb upstream.

Do the proper cleanup in case the size check fails.

Tested with xfstests:generic/228

Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 0cbade02 ("fuse: honor RLIMIT_FSIZE in fuse_file_fallocate")
Cc: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>