smbd: convert inherit_access_posix_acl() arg parent_dir to struct smb_filename

smbd: convert inherit_access_posix_acl() arg parent_dir to struct smb_filename

This also fixes a bug introduced by cea8e57eac2ed7b90a5c5d207bf392ff0546398e
where inherit_access_posix_acl() used the smb_fname->base_name instead of
inherit_from_dir in synthetic_smb_fname() to get an struct smb_filename of the
parent directory.

Nobody complained so far, fix it silently.

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>