NFSD: Add support for POSIX draft ACLs for file creation

NFSD: Add support for POSIX draft ACLs for file creation

NFSv4.2 clients can specify POSIX draft ACLs when creating file
objects via OPEN(CREATE) and CREATE operations. The previous patch
added POSIX ACL support to the NFSv4 SETATTR operation for modifying
existing objects, but file creation follows different code paths
that also require POSIX ACL handling.

This patch integrates POSIX ACL support into nfsd4_create() and
nfsd4_create_file(). Ownership of the decoded ACL pointers
(op_dpacl, op_pacl, cr_dpacl, cr_pacl) transfers to the nfsd_attrs
structure immediately, with the original fields cleared to NULL.
This transfer ensures nfsd_attrs_free() releases the ACLs upon
completion while preventing double-free on error paths.

Mutual exclusion between NFSv4 ACLs and POSIX ACLs is enforced:
setting both op_acl and op_dpacl/op_pacl simultaneously returns
nfserr_inval. Errors during ACL application clear the corresponding
bits in the result bitmask (fattr->bmval), signaling partial
completion to the client.

Signed-off-by: Rick Macklem <rmacklem@uoguelph.ca>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>