fusefs: correctly set fuse_release_in.flags in an error path

fuse_vnop_create must close the newly created file if it can't allocate a
vnode. When it does so, it must use the same file flags for FUSE_RELEASE as
it used for FUSE_OPEN or FUSE_CREATE.

Reported by: Coverity
Coverity CID: 1066204
Sponsored by: The FreeBSD Foundation