xfs: Add helper function xfs_attr_node_removename_setup

This patch adds a new helper function xfs_attr_node_removename_setup.
This will help modularize xfs_attr_node_removename when we add delay
ready attributes later.

Signed-off-by: Allison Collins <allison.henderson@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Chandan Rajendra <chandanrlinux@gmail.com>
[darrick: fix unused variable complaints by 0day robot]
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Acked-by: Dave Chinner <dchinner@redhat.com>
Reported-by: kernel test robot <lkp@intel.com>