NFSD: drop fh argument from alloc_init_deleg

Currently, we pass the fh of the opened file down through several
functions so that alloc_init_deleg can pass it to delegation_blocked.
The filehandle of the open file is available in the nfs4_file however,
so there's no need to pass it in a separate argument.

Drop the argument from alloc_init_deleg, nfs4_open_delegation and
nfs4_set_delegation.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>